diff options
50 files changed, 1063 insertions, 782 deletions
diff --git a/.github/ISSUE_TEMPLATE/bug_report.md b/.github/ISSUE_TEMPLATE/bug_report.md index 31152cd2..0d80f4a3 100644 --- a/.github/ISSUE_TEMPLATE/bug_report.md +++ b/.github/ISSUE_TEMPLATE/bug_report.md @@ -8,8 +8,9 @@ assignees: '' --- **IMPORTANT** -1. You have verified that the issue to be present in the current `dev` branch -2. Please supply the command line options and relevant environment variables, e.g. a copy-paste of the contents of `out/default/fuzzer_setup` +1. You have verified that the issue to be present in the current `dev` branch. +2. Please supply the command line options and relevant environment variables, + e.g., a copy-paste of the contents of `out/default/fuzzer_setup`. Thank you for making AFL++ better! diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md index c36ed9d8..fb13b91a 100644 --- a/CONTRIBUTING.md +++ b/CONTRIBUTING.md @@ -1,4 +1,4 @@ -# How to submit a Pull Request to AFLplusplus +# How to submit a Pull Request to AFL++ All contributions (pull requests) must be made against our `dev` branch. @@ -15,10 +15,9 @@ project, or added a file in a directory we already format, otherwise run: ./.custom-format.py -i file-that-you-have-created.c ``` -Regarding the coding style, please follow the AFL style. -No camel case at all and use AFL's macros wherever possible -(e.g. WARNF, FATAL, MAP_SIZE, ...). +Regarding the coding style, please follow the AFL style. No camel case at all +and use AFL's macros wherever possible (e.g., WARNF, FATAL, MAP_SIZE, ...). -Remember that AFLplusplus has to build and run on many platforms, so -generalize your Makefiles/GNUmakefile (or your patches to our pre-existing -Makefiles) to be as generic as possible. +Remember that AFL++ has to build and run on many platforms, so generalize your +Makefiles/GNUmakefile (or your patches to our pre-existing Makefiles) to be as +generic as possible.
\ No newline at end of file @@ -28,10 +28,11 @@ terms of the Apache-2.0 License. See the [LICENSE](LICENSE) for details. Here is some information to get you started: -* For releases, please see the +* For releases, see the [Releases tab](https://github.com/AFLplusplus/AFLplusplus/releases) and [branches](#branches). Also take a look at the list of - [important changes in AFL++](docs/important_changes.md). + [important changes in AFL++](docs/important_changes.md) and the list of + [features](docs/features.md). * If you want to use AFL++ for your academic work, check the [papers page](https://aflplus.plus/papers/) on the website. * To cite our work, look at the [Cite](#cite) section. @@ -44,8 +45,8 @@ Here is some information to get you started: ## Building and installing AFL++ -To have AFL++ easily available with everything compiled, pull the image -directly from the Docker Hub: +To have AFL++ easily available with everything compiled, pull the image directly +from the Docker Hub: ```shell docker pull aflplusplus/aflplusplus @@ -53,8 +54,8 @@ docker run -ti -v /location/of/your/target:/src aflplusplus/aflplusplus ``` This image is automatically generated when a push to the stable repo happens -(see [branches](#branches)). You will find your target source -code in `/src` in the container. +(see [branches](#branches)). You will find your target source code in `/src` in +the container. To build AFL++ yourself, continue at [docs/INSTALL.md](docs/INSTALL.md). @@ -86,7 +87,7 @@ Step-by-step quick start: ``` 2. Get a small but valid input file that makes sense to the program. When - fuzzing verbose syntax (SQL, HTTP, etc), create a dictionary as described in + fuzzing verbose syntax (SQL, HTTP, etc.), create a dictionary as described in [dictionaries/README.md](dictionaries/README.md), too. 3. If the program reads from stdin, run `afl-fuzz` like so: @@ -99,7 +100,7 @@ Step-by-step quick start: To add a dictionary, add `-x /path/to/dictionary.txt` to afl-fuzz. If the program takes input from a file, you can put `@@` in the program's - command line; AFL will put an auto-generated file name in there for you. + command line; AFL++ will put an auto-generated file name in there for you. 4. Investigate anything shown in red in the fuzzer UI by promptly consulting [docs/afl-fuzz_approach.md#understanding-the-status-screen](docs/afl-fuzz_approach.md#understanding-the-status-screen). @@ -120,8 +121,8 @@ Questions? Concerns? Bug reports? * The contributors can be reached via [https://github.com/AFLplusplus/AFLplusplus](https://github.com/AFLplusplus/AFLplusplus). -* Take a look at our [FAQ](docs/FAQ.md). If you find an interesting or - important question missing, submit it via +* Take a look at our [FAQ](docs/FAQ.md). If you find an interesting or important + question missing, submit it via [https://github.com/AFLplusplus/AFLplusplus/discussions](https://github.com/AFLplusplus/AFLplusplus/discussions). * There is a mailing list for the AFL/AFL++ project ([browse archive](https://groups.google.com/group/afl-users)). To compare @@ -133,10 +134,16 @@ Questions? Concerns? Bug reports? The following branches exist: -* [release](https://github.com/AFLplusplus/AFLplusplus/tree/release): the latest release -* [stable/trunk](https://github.com/AFLplusplus/AFLplusplus/): stable state of AFL++ - it is synced from dev from time to time when we are satisfied with its stability -* [dev](https://github.com/AFLplusplus/AFLplusplus/tree/dev): development state of AFL++ - bleeding edge and you might catch a checkout which does not compile or has a bug. *We only accept PRs in dev!!* -* (any other): experimental branches to work on specific features or testing new functionality or changes. +* [release](https://github.com/AFLplusplus/AFLplusplus/tree/release): the latest + release +* [stable/trunk](https://github.com/AFLplusplus/AFLplusplus/): stable state of + AFL++ - it is synced from dev from time to time when we are satisfied with its + stability +* [dev](https://github.com/AFLplusplus/AFLplusplus/tree/dev): development state + of AFL++ - bleeding edge and you might catch a checkout which does not compile + or has a bug. *We only accept PRs in dev!!* +* (any other): experimental branches to work on specific features or testing new + functionality or changes. ## Help wanted @@ -16,18 +16,17 @@ ## Further down the road -qemu_mode/frida_mode: +QEMU mode/FRIDA mode: - non colliding instrumentation - rename qemu specific envs to AFL_QEMU (AFL_ENTRYPOINT, AFL_CODE_START/END, AFL_COMPCOV_LEVEL?) - - add AFL_QEMU_EXITPOINT (maybe multiple?), maybe pointless as we have + - add AFL_QEMU_EXITPOINT (maybe multiple?), maybe pointless as there is persistent mode - ## Ideas - LTO/sancov: write current edge to prev_loc and use that information when - using cmplog or __sanitizer_cov_trace_cmp*. maybe we can deduct by follow - up edge numbers that both following cmp paths have been found and then - disable working on this edge id -> cmplog_intelligence branch - - use cmplog colorization taint result for havoc locations? + using cmplog or __sanitizer_cov_trace_cmp*. maybe we can deduct by follow up + edge numbers that both following cmp paths have been found and then disable + working on this edge id -> cmplog_intelligence branch + - use cmplog colorization taint result for havoc locations?
\ No newline at end of file diff --git a/coresight_mode/README.md b/coresight_mode/README.md index cd1bccab..1a39d347 100644 --- a/coresight_mode/README.md +++ b/coresight_mode/README.md @@ -3,7 +3,7 @@ CoreSight mode enables binary-only fuzzing on ARM64 Linux using CoreSight (ARM's hardware tracing technology). NOTE: CoreSight mode is in the early development stage. Not applicable for production use. -Currently the following hardware boards are supported: +Currently the following hardware boards are supported: * NVIDIA Jetson TX2 (NVIDIA Parker) * NVIDIA Jetson Nano (NVIDIA Tegra X1) * GIGABYTE R181-T90 (Marvell ThunderX2 CN99XX) @@ -12,7 +12,10 @@ Currently the following hardware boards are supported: Please read the [RICSec/coresight-trace README](https://github.com/RICSecLab/coresight-trace/blob/master/README.md) and check the prerequisites (capstone) before getting started. -CoreSight mode supports the AFL fork server mode to reduce `exec` system call overhead. To support it for binary-only fuzzing, it needs to modify the target ELF binary to re-link to the patched glibc. We employ this design from [PTrix](https://github.com/junxzm1990/afl-pt). +CoreSight mode supports the AFL++ fork server mode to reduce `exec` system call +overhead. To support it for binary-only fuzzing, it needs to modify the target +ELF binary to re-link to the patched glibc. We employ this design from +[PTrix](https://github.com/junxzm1990/afl-pt). Check out all the git submodules in the `cs_mode` directory: diff --git a/custom_mutators/README.md b/custom_mutators/README.md index fa877f34..0289e150 100644 --- a/custom_mutators/README.md +++ b/custom_mutators/README.md @@ -15,6 +15,7 @@ In `./rust`, you will find rust bindings, including a simple example in `./rust/ If you use git to clone AFL++, then the following will incorporate our excellent grammar custom mutator: + ```sh git submodule update --init ``` diff --git a/custom_mutators/gramatron/README.md b/custom_mutators/gramatron/README.md index 91f93355..8aa0cc44 100644 --- a/custom_mutators/gramatron/README.md +++ b/custom_mutators/gramatron/README.md @@ -1,19 +1,19 @@ # GramaTron -Gramatron is a coverage-guided fuzzer that uses grammar automatons to perform -grammar-aware fuzzing. Technical details about our framework are available -in the [ISSTA'21 paper](https://nebelwelt.net/files/21ISSTA.pdf). -The artifact to reproduce the experiments presented in the paper are present -in `artifact/`. Instructions to run a sample campaign and incorporate new -grammars is presented below: +GramaTron is a coverage-guided fuzzer that uses grammar automatons to perform +grammar-aware fuzzing. Technical details about our framework are available in +the [ISSTA'21 paper](https://nebelwelt.net/files/21ISSTA.pdf). The artifact to +reproduce the experiments presented in the paper are present in `artifact/`. +Instructions to run a sample campaign and incorporate new grammars is presented +below: -# Compiling +## Compiling -Simply execute `./build_gramatron_mutator.sh` +Execute `./build_gramatron_mutator.sh`. -# Running +## Running -You have to set the grammar file to use with `GRAMMATRON_AUTOMATION`: +You have to set the grammar file to use with `GRAMATRON_AUTOMATION`: ``` export AFL_DISABLE_TRIM=1 @@ -23,23 +23,27 @@ export GRAMATRON_AUTOMATION=grammars/ruby/source_automata.json afl-fuzz -i in -o out -- ./target ``` -# Adding and testing a new grammar +## Adding and testing a new grammar -- Specify in a JSON format for CFG. Examples are correspond `source.json` files +- Specify in a JSON format for CFG. Examples are correspond `source.json` files. - Run the automaton generation script (in `src/gramfuzz-mutator/preprocess`) which will place the generated automaton in the same folder. -``` -./preprocess/prep_automaton.sh <grammar_file> <start_symbol> [stack_limit] -Eg. ./preprocess/prep_automaton.sh ~/grammars/ruby/source.json PROGRAM -``` -- If the grammar has no self-embedding rules then you do not need to pass the - stack limit parameter. However, if it does have self-embedding rules then you + ``` + ./preprocess/prep_automaton.sh <grammar_file> <start_symbol> [stack_limit] + + E.g., ./preprocess/prep_automaton.sh ~/grammars/ruby/source.json PROGRAM + ``` + +- If the grammar has no self-embedding rules, then you do not need to pass the + stack limit parameter. However, if it does have self-embedding rules, then you need to pass the stack limit parameter. We recommend starting with `5` and - then increasing it if you need more complexity -- To sanity-check that the automaton is generating inputs as expected you can use the `test` binary housed in `src/gramfuzz-mutator` -``` -./test SanityCheck <automaton_file> + then increasing it if you need more complexity. +- To sanity-check that the automaton is generating inputs as expected, you can + use the `test` binary housed in `src/gramfuzz-mutator`. -Eg. ./test SanityCheck ~/grammars/ruby/source_automata.json -``` + ``` + ./test SanityCheck <automaton_file> + + E.g., ./test SanityCheck ~/grammars/ruby/source_automata.json + ```
\ No newline at end of file diff --git a/custom_mutators/libfuzzer/README.md b/custom_mutators/libfuzzer/README.md index fb3025f2..cb4773b7 100644 --- a/custom_mutators/libfuzzer/README.md +++ b/custom_mutators/libfuzzer/README.md @@ -11,9 +11,11 @@ Note that this is currently a simple implementation and it is missing two featur * Dictionary support To update the source, all that is needed is that FuzzerDriver.cpp has to receive + ``` #include "libfuzzer.inc" ``` + before the closing namespace bracket. It is also libfuzzer.inc where the configuration of the libfuzzer mutations @@ -21,4 +23,4 @@ are done. > Original repository: https://github.com/llvm/llvm-project > Path: compiler-rt/lib/fuzzer/*.{h|cpp} -> Source commit: df3e903655e2499968fc7af64fb5fa52b2ee79bb +> Source commit: df3e903655e2499968fc7af64fb5fa52b2ee79bb
\ No newline at end of file diff --git a/dictionaries/README.md b/dictionaries/README.md index 7c587abb..0b3b4d90 100644 --- a/dictionaries/README.md +++ b/dictionaries/README.md @@ -1,20 +1,18 @@ -# AFL dictionaries +# AFL++ dictionaries (See [../README.md](../README.md) for the general instruction manual.) -This subdirectory contains a set of dictionaries that can be used in -conjunction with the -x option to allow the fuzzer to effortlessly explore the -grammar of some of the more verbose data formats or languages. The basic -principle behind the operation of fuzzer dictionaries is outlined in section 10 -of the "main" README.md for the project. +This subdirectory contains a set of dictionaries that can be used in conjunction +with the -x option to allow the fuzzer to effortlessly explore the grammar of +some of the more verbose data formats or languages. -These sets were done by Michal Zalewski, various contributors, and imported -from oss-fuzz, go-fuzz and libfuzzer. +These sets were done by Michal Zalewski, various contributors, and imported from +oss-fuzz, go-fuzz and libfuzzer. Custom dictionaries can be added at will. They should consist of a reasonably-sized set of rudimentary syntax units that the fuzzer will then try -to clobber together in various ways. Snippets between 2 and 16 bytes are -usually the sweet spot. +to clobber together in various ways. Snippets between 2 and 16 bytes are usually +the sweet spot. Custom dictionaries can be created in two ways: @@ -36,9 +34,9 @@ In the file mode, every name field can be optionally followed by @<num>, e.g.: `keyword_foo@1 = "foo"` Such entries will be loaded only if the requested dictionary level is equal or -higher than this number. The default level is zero; a higher value can be set -by appending @<num> to the dictionary file name, like so: +higher than this number. The default level is zero; a higher value can be set by +appending @<num> to the dictionary file name, like so: `-x path/to/dictionary.dct@2` -Good examples of dictionaries can be found in xml.dict and png.dict. +Good examples of dictionaries can be found in xml.dict and png.dict.
\ No newline at end of file diff --git a/docs/FAQ.md b/docs/FAQ.md index 34ed4cf5..7869ee61 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -8,32 +8,47 @@ If you find an interesting or important question missing, submit it via <details> <summary id="what-is-the-difference-between-afl-and-aflplusplus">What is the difference between AFL and AFL++?</summary><p> - AFL++ is a superior fork to Google's AFL - more speed, more and better mutations, more and better instrumentation, custom module support, etc. - - American Fuzzy Lop (AFL) was developed by Michał "lcamtuf" Zalewski starting in 2013/2014, and when he left Google end of 2017 he stopped developing it. - - At the end of 2019, the Google fuzzing team took over maintenance of AFL, however it is only accepting PRs from the community and is not developing enhancements anymore. - - In the second quarter of 2019, 1 1/2 years later, when no further development of AFL had happened and it became clear there would none be coming, AFL++ was born, where initially community patches were collected and applied for bug fixes and enhancements. - Then from various AFL spin-offs - mostly academic research - features were integrated. - This already resulted in a much advanced AFL. - - Until the end of 2019, the AFL++ team had grown to four active developers which then implemented their own research and features, making it now by far the most flexible and feature rich guided fuzzer available as open source. - And in independent fuzzing benchmarks it is one of the best fuzzers available, e.g. [Fuzzbench Report](https://www.fuzzbench.com/reports/2020-08-03/index.html). + AFL++ is a superior fork to Google's AFL - more speed, more and better + mutations, more and better instrumentation, custom module support, etc. + + American Fuzzy Lop (AFL) was developed by Michał "lcamtuf" Zalewski starting + in 2013/2014, and when he left Google end of 2017 he stopped developing it. + + At the end of 2019, the Google fuzzing team took over maintenance of AFL, + however, it is only accepting PRs from the community and is not developing + enhancements anymore. + + In the second quarter of 2019, 1 1/2 years later, when no further development + of AFL had happened and it became clear there would none be coming, AFL++ was + born, where initially community patches were collected and applied for bug + fixes and enhancements. Then from various AFL spin-offs - mostly academic + research - features were integrated. This already resulted in a much advanced + AFL. + + Until the end of 2019, the AFL++ team had grown to four active developers + which then implemented their own research and features, making it now by far + the most flexible and feature rich guided fuzzer available as open source. And + in independent fuzzing benchmarks it is one of the best fuzzers available, + e.g., [Fuzzbench + Report](https://www.fuzzbench.com/reports/2020-08-03/index.html). </p></details> <details> <summary id="where-can-i-find-tutorials">Where can I find tutorials?</summary><p> - We compiled a list of tutorials and exercises, see [tutorials.md](tutorials.md). + We compiled a list of tutorials and exercises, see + [tutorials.md](tutorials.md). </p></details> <details> <summary id="what-is-an-edge">What is an "edge"?</summary><p> A program contains `functions`, `functions` contain the compiled machine code. - The compiled machine code in a `function` can be in a single or many `basic blocks`. - A `basic block` is the largest possible number of subsequent machine code instructions that has exactly one entrypoint (which can be be entered by multiple other basic blocks) and runs linearly without branching or jumping to other addresses (except at the end). + The compiled machine code in a `function` can be in a single or many `basic + blocks`. A `basic block` is the largest possible number of subsequent machine + code instructions that has exactly one entry point (which can be be entered by + multiple other basic blocks) and runs linearly without branching or jumping to + other addresses (except at the end). ``` function() { @@ -55,7 +70,8 @@ If you find an interesting or important question missing, submit it via Every code block between two jump locations is a `basic block`. - An `edge` is then the unique relationship between two directly connected `basic blocks` (from the code example above): + An `edge` is then the unique relationship between two directly connected + `basic blocks` (from the code example above): ``` Block A @@ -70,8 +86,8 @@ If you find an interesting or important question missing, submit it via Block E ``` - Every line between two blocks is an `edge`. - Note that a few basic block loop to itself, this too would be an edge. + Every line between two blocks is an `edge`. Note that a few basic block loop + to itself, this too would be an edge. </p></details> ## Targets @@ -81,7 +97,8 @@ If you find an interesting or important question missing, submit it via AFL++ is a great fuzzer if you have the source code available. - However, if there is only the binary program and no source code available, then the standard non-instrumented mode is not effective. + However, if there is only the binary program and no source code available, + then the standard non-instrumented mode is not effective. To learn how these binaries can be fuzzed, read [fuzzing_binary-only_targets.md](fuzzing_binary-only_targets.md). @@ -92,15 +109,19 @@ If you find an interesting or important question missing, submit it via The short answer is - you cannot, at least not "out of the box". - For more information on fuzzing network services, see [best_practices.md#fuzzing-a-network-service](best_practices.md#fuzzing-a-network-service). + For more information on fuzzing network services, see + [best_practices.md#fuzzing-a-network-service](best_practices.md#fuzzing-a-network-service). </p></details> <details> <summary id="how-can-i-fuzz-a-gui-program">How can I fuzz a GUI program?</summary><p> - Not all GUI programs are suitable for fuzzing. If the GUI program can read the fuzz data from a file without needing any user interaction, then it would be suitable for fuzzing. + Not all GUI programs are suitable for fuzzing. If the GUI program can read the + fuzz data from a file without needing any user interaction, then it would be + suitable for fuzzing. - For more information on fuzzing GUI programs, see [best_practices.md#fuzzing-a-gui-program](best_practices.md#fuzzing-a-gui-program). + For more information on fuzzing GUI programs, see + [best_practices.md#fuzzing-a-gui-program](best_practices.md#fuzzing-a-gui-program). </p></details> ## Performance @@ -108,25 +129,33 @@ If you find an interesting or important question missing, submit it via <details> <summary id="how-can-i-improve-the-fuzzing-speed">How can I improve the fuzzing speed?</summary><p> - There are a few things you can do to improve the fuzzing speed, see [best_practices.md#improving-speed](best_practices.md#improving-speed). + There are a few things you can do to improve the fuzzing speed, see + [best_practices.md#improving-speed](best_practices.md#improving-speed). </p></details> <details> <summary id="why-is-my-stability-below-100percent">Why is my stability below 100%?</summary><p> - Stability is measured by how many percent of the edges in the target are "stable". - Sending the same input again and again should take the exact same path through the target every time. - If that is the case, the stability is 100%. + Stability is measured by how many percent of the edges in the target are + "stable". Sending the same input again and again should take the exact same + path through the target every time. If that is the case, the stability is + 100%. - If however randomness happens, e.g. a thread reading other external data, reaction to timing, etc., then in some of the re-executions with the same data the edge coverage result will be different accross runs. - Those edges that change are then flagged "unstable". + If, however, randomness happens, e.g., a thread reading other external data, + reaction to timing, etc., then in some of the re-executions with the same data + the edge coverage result will be different across runs. Those edges that + change are then flagged "unstable". - The more "unstable" edges, the more difficult for AFL++ to identify valid new paths. + The more "unstable" edges, the more difficult for AFL++ to identify valid new + paths. - A value above 90% is usually fine and a value above 80% is also still ok, and even a value above 20% can still result in successful finds of bugs. - However, it is recommended that for values below 90% or 80% you should take countermeasures to improve stability. + A value above 90% is usually fine and a value above 80% is also still ok, and + even a value above 20% can still result in successful finds of bugs. However, + it is recommended that for values below 90% or 80% you should take + countermeasures to improve stability. - For more information on stability and how to improve the stability value, see [best_practices.md#improving-stability](best_practices.md#improving-stability). + For more information on stability and how to improve the stability value, see + [best_practices.md#improving-stability](best_practices.md#improving-stability). </p></details> ## Troubleshooting @@ -134,7 +163,8 @@ If you find an interesting or important question missing, submit it via <details> <summary id="i-got-a-weird-compile-error-from-clang">I got a weird compile error from clang.</summary><p> - If you see this kind of error when trying to instrument a target with afl-cc/afl-clang-fast/afl-clang-lto: + If you see this kind of error when trying to instrument a target with + afl-cc/afl-clang-fast/afl-clang-lto: ``` /prg/tmp/llvm-project/build/bin/clang-13: symbol lookup error: /usr/local/bin/../lib/afl//cmplog-instructions-pass.so: undefined symbol: _ZNK4llvm8TypeSizecvmEv @@ -148,7 +178,8 @@ If you find an interesting or important question missing, submit it via ******************** ``` - Then this means that your OS updated the clang installation from an upgrade package and because of that the AFL++ llvm plugins do not match anymore. + Then this means that your OS updated the clang installation from an upgrade + package and because of that the AFL++ llvm plugins do not match anymore. Solution: `git pull ; make clean install` of AFL++. </p></details>
\ No newline at end of file diff --git a/docs/INSTALL.md b/docs/INSTALL.md index cfa20dea..906d3f8e 100644 --- a/docs/INSTALL.md +++ b/docs/INSTALL.md @@ -3,7 +3,8 @@ ## Linux on x86 An easy way to install AFL++ with everything compiled is available via docker: -You can use the [Dockerfile](../Dockerfile) (which has gcc-10 and clang-11 - hence afl-clang-lto is available!) or just pull directly from the Docker Hub: +You can use the [Dockerfile](../Dockerfile) (which has gcc-10 and clang-11 - +hence afl-clang-lto is available!) or just pull directly from the Docker Hub: ```shell docker pull aflplusplus/aflplusplus @@ -13,26 +14,29 @@ docker run -ti -v /location/of/your/target:/src aflplusplus/aflplusplus This image is automatically generated when a push to the stable repo happens. You will find your target source code in /src in the container. -If you want to build AFL++ yourself, you have many options. -The easiest choice is to build and install everything: +If you want to build AFL++ yourself, you have many options. The easiest choice +is to build and install everything: ```shell sudo apt-get update sudo apt-get install -y build-essential python3-dev automake git flex bison libglib2.0-dev libpixman-1-dev python3-setuptools # try to install llvm 11 and install the distro default if that fails -sudo apt-get install -y lld-11 llvm-11 llvm-11-dev clang-11 || sudo apt-get install -y lld llvm llvm-dev clang +sudo apt-get install -y lld-11 llvm-11 llvm-11-dev clang-11 || sudo apt-get install -y lld llvm llvm-dev clang sudo apt-get install -y gcc-$(gcc --version|head -n1|sed 's/.* //'|sed 's/\..*//')-plugin-dev libstdc++-$(gcc --version|head -n1|sed 's/.* //'|sed 's/\..*//')-dev -sudo apt-get install -y ninja-build # for qemu_mode +sudo apt-get install -y ninja-build # for QEMU mode git clone https://github.com/AFLplusplus/AFLplusplus cd AFLplusplus make distrib sudo make install ``` -It is recommended to install the newest available gcc, clang and llvm-dev possible in your distribution! +It is recommended to install the newest available gcc, clang and llvm-dev +possible in your distribution! -Note that "make distrib" also builds instrumentation, qemu_mode, unicorn_mode and more. -If you just want plain AFL++, then do "make all". However, compiling and using at least instrumentation is highly recommended for much better results - hence in this case choose: +Note that "make distrib" also builds instrumentation, QEMU mode, unicorn_mode +and more. If you just want plain AFL++, then do "make all". However, compiling +and using at least instrumentation is highly recommended for much better results +- hence in this case choose: ```shell make source-only @@ -41,19 +45,24 @@ make source-only These build targets exist: * all: just the main AFL++ binaries -* binary-only: everything for binary-only fuzzing: qemu_mode, unicorn_mode, libdislocator, libtokencap -* source-only: everything for source code fuzzing: instrumentation, libdislocator, libtokencap +* binary-only: everything for binary-only fuzzing: qemu_mode, unicorn_mode, + libdislocator, libtokencap +* source-only: everything for source code fuzzing: instrumentation, + libdislocator, libtokencap * distrib: everything (for both binary-only and source code fuzzing) * man: creates simple man pages from the help option of the programs * install: installs everything you have compiled with the build options above * clean: cleans everything compiled, not downloads (unless not on a checkout) * deepclean: cleans everything including downloads * code-format: format the code, do this before you commit and send a PR please! -* tests: runs test cases to ensure that all features are still working as they should +* tests: runs test cases to ensure that all features are still working as they + should * unit: perform unit tests (based on cmocka) * help: shows these build options -[Unless you are on Mac OS X](https://developer.apple.com/library/archive/qa/qa1118/_index.html), you can also build statically linked versions of the AFL++ binaries by passing the `STATIC=1` argument to make: +[Unless you are on Mac OS X](https://developer.apple.com/library/archive/qa/qa1118/_index.html), +you can also build statically linked versions of the AFL++ binaries by passing +the `STATIC=1` argument to make: ```shell make STATIC=1 @@ -67,23 +76,27 @@ These build options exist: * PROFILING - compile with profiling information (gprof) * INTROSPECTION - compile afl-fuzz with mutation introspection * NO_PYTHON - disable python support -* NO_SPLICING - disables splicing mutation in afl-fuzz, not recommended for normal fuzzing +* NO_SPLICING - disables splicing mutation in afl-fuzz, not recommended for + normal fuzzing * AFL_NO_X86 - if compiling on non-intel/amd platforms -* LLVM_CONFIG - if your distro doesn't use the standard name for llvm-config (e.g. Debian) +* LLVM_CONFIG - if your distro doesn't use the standard name for llvm-config + (e.g., Debian) e.g.: `make ASAN_BUILD=1` ## MacOS X on x86 and arm64 (M1) -MacOS X should work, but there are some gotchas due to the idiosyncrasies of the platform. -On top of this, we have limited release testing capabilities and depend mostly on user feedback. +MacOS X should work, but there are some gotchas due to the idiosyncrasies of the +platform. On top of this, we have limited release testing capabilities and +depend mostly on user feedback. -To build AFL, install llvm (and perhaps gcc) from brew and follow the general instructions for Linux. -If possible, avoid Xcode at all cost. +To build AFL, install llvm (and perhaps gcc) from brew and follow the general +instructions for Linux. If possible, avoid Xcode at all cost. `brew install wget git make cmake llvm gdb` -Be sure to setup `PATH` to point to the correct clang binaries and use the freshly installed clang, clang++ and gmake, e.g.: +Be sure to setup `PATH` to point to the correct clang binaries and use the +freshly installed clang, clang++ and gmake, e.g.: ``` export PATH="/usr/local/Cellar/llvm/12.0.1/bin/:$PATH" @@ -96,33 +109,35 @@ cd .. gmake install ``` -`afl-gcc` will fail unless you have GCC installed, but that is using outdated instrumentation anyway. -You don't want that. -Note that `afl-clang-lto`, `afl-gcc-fast` and `qemu_mode` are not working on MacOS. +`afl-gcc` will fail unless you have GCC installed, but that is using outdated +instrumentation anyway. You don't want that. Note that `afl-clang-lto`, +`afl-gcc-fast` and `qemu_mode` are not working on MacOS. -The crash reporting daemon that comes by default with MacOS X will cause problems with fuzzing. -You need to turn it off: +The crash reporting daemon that comes by default with MacOS X will cause +problems with fuzzing. You need to turn it off: ``` launchctl unload -w /System/Library/LaunchAgents/com.apple.ReportCrash.plist sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.ReportCrash.Root.plist ``` -The `fork()` semantics on OS X are a bit unusual compared to other unix systems and definitely don't look POSIX-compliant. -This means two things: +The `fork()` semantics on OS X are a bit unusual compared to other unix systems +and definitely don't look POSIX-compliant. This means two things: - Fuzzing will be probably slower than on Linux. In fact, some folks report considerable performance gains by running the jobs inside a Linux VM on MacOS X. - - Some non-portable, platform-specific code may be incompatible with the - AFL forkserver. If you run into any problems, set `AFL_NO_FORKSRV=1` in the + - Some non-portable, platform-specific code may be incompatible with the AFL++ + forkserver. If you run into any problems, set `AFL_NO_FORKSRV=1` in the environment before starting afl-fuzz. -User emulation mode of QEMU does not appear to be supported on MacOS X, so black-box instrumentation mode (`-Q`) will not work. -However, Frida mode (`-O`) should work on x86 and arm64 MacOS boxes. +User emulation mode of QEMU does not appear to be supported on MacOS X, so +black-box instrumentation mode (`-Q`) will not work. However, Frida mode (`-O`) +should work on x86 and arm64 MacOS boxes. -MacOS X supports SYSV shared memory used by AFL's instrumentation, but the default settings aren't usable with AFL++. -The default settings on 10.14 seem to be: +MacOS X supports SYSV shared memory used by AFL's instrumentation, but the +default settings aren't usable with AFL++. The default settings on 10.14 seem to +be: ```bash $ ipcs -M @@ -135,14 +150,16 @@ shminfo: shmall: 1024 (max amount of shared memory in pages) ``` -To temporarily change your settings to something minimally usable with AFL++, run these commands as root: +To temporarily change your settings to something minimally usable with AFL++, +run these commands as root: ```bash sysctl kern.sysv.shmmax=8388608 sysctl kern.sysv.shmall=4096 ``` -If you're running more than one instance of AFL, you likely want to make `shmall` bigger and increase `shmseg` as well: +If you're running more than one instance of AFL, you likely want to make +`shmall` bigger and increase `shmseg` as well: ```bash sysctl kern.sysv.shmmax=8388608 @@ -150,4 +167,6 @@ sysctl kern.sysv.shmseg=48 sysctl kern.sysv.shmall=98304 ``` -See [https://www.spy-hill.com/help/apple/SharedMemory.html](https://www.spy-hill.com/help/apple/SharedMemory.html) for documentation for these settings and how to make them permanent.
\ No newline at end of file +See +[http://www.spy-hill.com/help/apple/SharedMemory.html](http://www.spy-hill.com/help/apple/SharedMemory.html) +for documentation for these settings and how to make them permanent.
\ No newline at end of file diff --git a/docs/afl-fuzz_approach.md b/docs/afl-fuzz_approach.md index e0d5a1c9..2da61cc4 100644 --- a/docs/afl-fuzz_approach.md +++ b/docs/afl-fuzz_approach.md @@ -37,7 +37,7 @@ superior to blind fuzzing or coverage-only tools. ## Understanding the status screen -This chapter provides an overview of the status screen - plus tips for +This section provides an overview of the status screen - plus tips for troubleshooting any warnings and red text shown in the UI. For the general instruction manual, see [README.md](../README.md). @@ -103,8 +103,8 @@ will be allowed to run for months. There's one important thing to watch out for: if the tool is not finding new paths within several minutes of starting, you're probably not invoking the -target binary correctly and it never gets to parse the input files we're -throwing at it; other possible explanations are that the default memory limit +target binary correctly and it never gets to parse the input files that are +thrown at it; other possible explanations are that the default memory limit (`-m`) is too restrictive and the program exits after failing to allocate a buffer very early on; or that the input files are patently invalid and always fail a basic header check. @@ -172,10 +172,9 @@ processed path is not "favored" (a property discussed later on). The section provides some trivia about the coverage observed by the instrumentation embedded in the target binary. -The first line in the box tells you how many branch tuples we have already hit, -in proportion to how much the bitmap can hold. The number on the left describes -the current input; the one on the right is the value for the entire input -corpus. +The first line in the box tells you how many branch tuples already were hit, in +proportion to how much the bitmap can hold. The number on the left describes the +current input; the one on the right is the value for the entire input corpus. Be wary of extremes: @@ -194,7 +193,7 @@ Be wary of extremes: The other line deals with the variability in tuple hit counts seen in the binary. In essence, if every taken branch is always taken a fixed number of -times for all the inputs we have tried, this will read `1.00`. As we manage to +times for all the inputs that were tried, this will read `1.00`. As we manage to trigger other hit counts for every branch, the needle will start to move toward `8.00` (every bit in the 8-bit map hit), but will probably never reach that extreme. @@ -244,9 +243,10 @@ now. It tells you about the current stage, which can be any of: together two random inputs from the queue at some arbitrarily selected midpoint. - sync - a stage used only when `-M` or `-S` is set (see - [parallel_fuzzing.md](parallel_fuzzing.md)). No real fuzzing is involved, but - the tool scans the output from other fuzzers and imports test cases as - necessary. The first time this is done, it may take several minutes or so. + [fuzzing_in_depth.md:3c) Using multiple cores](fuzzing_in_depth.md#c-using-multiple-cores)). + No real fuzzing is involved, but the tool scans the output from other fuzzers + and imports test cases as necessary. The first time this is done, it may take + several minutes or so. The remaining fields should be fairly self-evident: there's the exec count progress indicator for the current stage, a global exec counter, and a benchmark @@ -255,8 +255,8 @@ to another, but the benchmark should be ideally over 500 execs/sec most of the time - and if it stays below 100, the job will probably take very long. The fuzzer will explicitly warn you about slow targets, too. If this happens, -see the [perf_tips.md](perf_tips.md) file included with the fuzzer for ideas on -how to speed things up. +see the [best_practices.md#improving-speed](best_practices.md#improving-speed) +for ideas on how to speed things up. ### Findings in depth @@ -295,9 +295,9 @@ exceed it by a margin sufficient to be classified as hangs. +-----------------------------------------------------+ ``` -This is just another nerd-targeted section keeping track of how many paths we -have netted, in proportion to the number of execs attempted, for each of the -fuzzing strategies discussed earlier on. This serves to convincingly validate +This is just another nerd-targeted section keeping track of how many paths were +netted, in proportion to the number of execs attempted, for each of the fuzzing +strategies discussed earlier on. This serves to convincingly validate assumptions about the usefulness of the various approaches taken by afl-fuzz. The trim strategy stats in this section are a bit different than the rest. The @@ -339,16 +339,16 @@ fuzzing yet. The same stat is also given for "favored" entries that the fuzzer really wants to get to in this queue cycle (the non-favored entries may have to wait a couple of cycles to get their chance). -Next, we have the number of new paths found during this fuzzing section and -imported from other fuzzer instances when doing parallelized fuzzing; and the -extent to which identical inputs appear to sometimes produce variable behavior -in the tested binary. +Next is the number of new paths found during this fuzzing section and imported +from other fuzzer instances when doing parallelized fuzzing; and the extent to +which identical inputs appear to sometimes produce variable behavior in the +tested binary. That last bit is actually fairly interesting: it measures the consistency of observed traces. If a program always behaves the same for the same input data, it will earn a score of 100%. When the value is lower but still shown in purple, the fuzzing process is unlikely to be negatively affected. If it goes into red, -you may be in trouble, since AFL will have difficulty discerning between +you may be in trouble, since AFL++ will have difficulty discerning between meaningful and "phantom" effects of tweaking the input file. Now, most targets will just get a 100% score, but when you see lower figures, @@ -397,7 +397,8 @@ comparing it to the number of logical cores on the system. If the value is shown in green, you are using fewer CPU cores than available on your system and can probably parallelize to improve performance; for tips on how -to do that, see [parallel_fuzzing.md](parallel_fuzzing.md). +to do that, see +[fuzzing_in_depth.md:3c) Using multiple cores](fuzzing_in_depth.md#c-using-multiple-cores). If the value is shown in red, your CPU is *possibly* oversubscribed, and running additional fuzzers may not give you any benefits. @@ -425,8 +426,7 @@ There are three subdirectories created within the output directory and updated in real-time: - queue/ - test cases for every distinctive execution path, plus all the - starting files given by the user. This is the synthesized corpus - mentioned in section 2. + starting files given by the user. This is the synthesized corpus. Before using this corpus for any other purposes, you can shrink it to a smaller size using the afl-cmin tool. The tool will find @@ -447,8 +447,8 @@ involve any state transitions not seen in previously-recorded faults. If a single bug can be reached in multiple ways, there will be some count inflation early in the process, but this should quickly taper off. -The file names for crashes and hangs are correlated with the parent, non-faulting -queue entries. This should help with debugging. +The file names for crashes and hangs are correlated with the parent, +non-faulting queue entries. This should help with debugging. ## Visualizing @@ -468,6 +468,8 @@ cd ../../ sudo make install ``` +To learn more about remote monitoring and metrics visualization with StatsD, see +[rpc_statsd.md](rpc_statsd.md). ### Addendum: status and plot files @@ -505,8 +507,8 @@ directory. This includes: - `peak_rss_mb` - max rss usage reached during fuzzing in MB - `edges_found` - how many edges have been found - `var_byte_count` - how many edges are non-deterministic -- `afl_banner` - banner text (e.g. the target name) -- `afl_version` - the version of AFL used +- `afl_banner` - banner text (e.g., the target name) +- `afl_version` - the version of AFL++ used - `target_mode` - default, persistent, qemu, unicorn, non-instrumented - `command_line` - full command line used for the fuzzing session @@ -523,9 +525,9 @@ into each of them or deploy scripts to read the fuzzer statistics. Using `AFL_STATSD` (and the other related environment variables `AFL_STATSD_HOST`, `AFL_STATSD_PORT`, `AFL_STATSD_TAGS_FLAVOR`) you can automatically send metrics to your favorite StatsD server. Depending on your StatsD server, you will be -able to monitor, trigger alerts, or perform actions based on these metrics (e.g: -alert on slow exec/s for a new build, threshold of crashes, time since last -crash > X, etc). +able to monitor, trigger alerts, or perform actions based on these metrics +(e.g.: alert on slow exec/s for a new build, threshold of crashes, time since +last crash > X, etc.). The selected metrics are a subset of all the metrics found in the status and in the plot file. The list is the following: `cycle_done`, `cycles_wo_finds`, @@ -536,6 +538,6 @@ the plot file. The list is the following: `cycle_done`, `cycles_wo_finds`, definitions can be found in the addendum above. When using multiple fuzzer instances with StatsD, it is *strongly* recommended -to setup the flavor (AFL_STATSD_TAGS_FLAVOR) to match your StatsD server. This +to setup the flavor (`AFL_STATSD_TAGS_FLAVOR`) to match your StatsD server. This will allow you to see individual fuzzer performance, detect bad ones, see the progress of each strategy...
\ No newline at end of file diff --git a/docs/best_practices.md b/docs/best_practices.md index 18096851..96c6e3c2 100644 --- a/docs/best_practices.md +++ b/docs/best_practices.md @@ -19,7 +19,8 @@ ### Fuzzing a target with source code available -To learn how to fuzz a target if source code is available, see [fuzzing_in_depth.md](fuzzing_in_depth.md). +To learn how to fuzz a target if source code is available, see +[fuzzing_in_depth.md](fuzzing_in_depth.md). ### Fuzzing a target with dlopen instrumented libraries @@ -48,11 +49,16 @@ For a comprehensive guide, see ### Fuzzing a GUI program -If the GUI program can read the fuzz data from a file (via the command line, a fixed location or via an environment variable) without needing any user interaction, then it would be suitable for fuzzing. +If the GUI program can read the fuzz data from a file (via the command line, a +fixed location or via an environment variable) without needing any user +interaction, then it would be suitable for fuzzing. -Otherwise, it is not possible without modifying the source code - which is a very good idea anyway as the GUI functionality is a huge CPU/time overhead for the fuzzing. +Otherwise, it is not possible without modifying the source code - which is a +very good idea anyway as the GUI functionality is a huge CPU/time overhead for +the fuzzing. -So create a new `main()` that just reads the test case and calls the functionality for processing the input that the GUI program is using. +So create a new `main()` that just reads the test case and calls the +functionality for processing the input that the GUI program is using. ### Fuzzing a network service @@ -61,87 +67,126 @@ Fuzzing a network service does not work "out of the box". Using a network channel is inadequate for several reasons: - it has a slow-down of x10-20 on the fuzzing speed - it does not scale to fuzzing multiple instances easily, -- instead of one initial data packet often a back-and-forth interplay of packets is needed for stateful protocols (which is totally unsupported by most coverage aware fuzzers). - -The established method to fuzz network services is to modify the source code -to read from a file or stdin (fd 0) (or even faster via shared memory, combine -this with persistent mode [instrumentation/README.persistent_mode.md](../instrumentation/README.persistent_mode.md) -and you have a performance gain of x10 instead of a performance loss of over -x10 - that is a x100 difference!). - -If modifying the source is not an option (e.g. because you only have a binary +- instead of one initial data packet often a back-and-forth interplay of packets + is needed for stateful protocols (which is totally unsupported by most + coverage aware fuzzers). + +The established method to fuzz network services is to modify the source code to +read from a file or stdin (fd 0) (or even faster via shared memory, combine this +with persistent mode +[instrumentation/README.persistent_mode.md](../instrumentation/README.persistent_mode.md) +and you have a performance gain of x10 instead of a performance loss of over x10 +- that is a x100 difference!). + +If modifying the source is not an option (e.g., because you only have a binary and perform binary fuzzing) you can also use a shared library with AFL_PRELOAD to emulate the network. This is also much faster than the real network would be. See [utils/socket_fuzzing/](../utils/socket_fuzzing/). There is an outdated AFL++ branch that implements networking if you are -desperate though: [https://github.com/AFLplusplus/AFLplusplus/tree/networking](https://github.com/AFLplusplus/AFLplusplus/tree/networking) - -however a better option is AFLnet ([https://github.com/aflnet/aflnet](https://github.com/aflnet/aflnet)) -which allows you to define network state with different type of data packets. +desperate though: +[https://github.com/AFLplusplus/AFLplusplus/tree/networking](https://github.com/AFLplusplus/AFLplusplus/tree/networking) +- however, a better option is AFLnet +([https://github.com/aflnet/aflnet](https://github.com/aflnet/aflnet)) which +allows you to define network state with different type of data packets. ## Improvements ### Improving speed -1. Use [llvm_mode](../instrumentation/README.llvm.md): afl-clang-lto (llvm >= 11) or afl-clang-fast (llvm >= 9 recommended). -2. Use [persistent mode](../instrumentation/README.persistent_mode.md) (x2-x20 speed increase). -3. Instrument just what you are interested in, see [instrumentation/README.instrument_list.md](../instrumentation/README.instrument_list.md). -4. If you do not use shmem persistent mode, use `AFL_TMPDIR` to put the input file directory on a tempfs location, see [env_variables.md](env_variables.md). -5. Improve Linux kernel performance: modify `/etc/default/grub`, set `GRUB_CMDLINE_LINUX_DEFAULT="ibpb=off ibrs=off kpti=off l1tf=off mds=off mitigations=off no_stf_barrier noibpb noibrs nopcid nopti nospec_store_bypass_disable nospectre_v1 nospectre_v2 pcid=off pti=off spec_store_bypass_disable=off spectre_v2=off stf_barrier=off"`; then `update-grub` and `reboot` (warning: makes the system less secure). -6. Running on an `ext2` filesystem with `noatime` mount option will be a bit faster than on any other journaling filesystem. -7. Use your cores ([fuzzing_in_depth.md:3c) Using multiple cores](fuzzing_in_depth.md#c-using-multiple-cores))! +1. Use [llvm_mode](../instrumentation/README.llvm.md): afl-clang-lto (llvm >= + 11) or afl-clang-fast (llvm >= 9 recommended). +2. Use [persistent mode](../instrumentation/README.persistent_mode.md) (x2-x20 + speed increase). +3. Instrument just what you are interested in, see + [instrumentation/README.instrument_list.md](../instrumentation/README.instrument_list.md). +4. If you do not use shmem persistent mode, use `AFL_TMPDIR` to put the input + file directory on a tempfs location, see + [env_variables.md](env_variables.md). +5. Improve Linux kernel performance: modify `/etc/default/grub`, set + `GRUB_CMDLINE_LINUX_DEFAULT="ibpb=off ibrs=off kpti=off l1tf=off mds=off + mitigations=off no_stf_barrier noibpb noibrs nopcid nopti + nospec_store_bypass_disable nospectre_v1 nospectre_v2 pcid=off pti=off + spec_store_bypass_disable=off spectre_v2=off stf_barrier=off"`; then + `update-grub` and `reboot` (warning: makes the system less secure). +6. Running on an `ext2` filesystem with `noatime` mount option will be a bit + faster than on any other journaling filesystem. +7. Use your cores + ([fuzzing_in_depth.md:3c) Using multiple cores](fuzzing_in_depth.md#c-using-multiple-cores))! ### Improving stability -For fuzzing a 100% stable target that covers all edges is the best case. -A 90% stable target that covers all edges is however better than a 100% stable target that ignores 10% of the edges. +For fuzzing a 100% stable target that covers all edges is the best case. A 90% +stable target that covers all edges is, however, better than a 100% stable +target that ignores 10% of the edges. -With instability, you basically have a partial coverage loss on an edge, with ignored functions you have a full loss on that edges. +With instability, you basically have a partial coverage loss on an edge, with +ignored functions you have a full loss on that edges. -There are functions that are unstable, but also provide value to coverage, e.g., init functions that use fuzz data as input. -If however a function that has nothing to do with the input data is the source of instability, e.g., checking jitter, or is a hash map function etc., then it should not be instrumented. +There are functions that are unstable, but also provide value to coverage, e.g., +init functions that use fuzz data as input. If, however, a function that has +nothing to do with the input data is the source of instability, e.g., checking +jitter, or is a hash map function etc., then it should not be instrumented. -To be able to exclude these functions (based on AFL++'s measured stability), the following process will allow to identify functions with variable edges. +To be able to exclude these functions (based on AFL++'s measured stability), the +following process will allow to identify functions with variable edges. -Four steps are required to do this and it also requires quite some knowledge of coding and/or disassembly and is effectively possible only with `afl-clang-fast` `PCGUARD` and `afl-clang-lto` `LTO` instrumentation. +Four steps are required to do this and it also requires quite some knowledge of +coding and/or disassembly and is effectively possible only with `afl-clang-fast` +`PCGUARD` and `afl-clang-lto` `LTO` instrumentation. 1. Instrument to be able to find the responsible function(s): - a) For LTO instrumented binaries, this can be documented during compile time, just set `export AFL_LLVM_DOCUMENT_IDS=/path/to/a/file`. - This file will have one assigned edge ID and the corresponding function per line. - - b) For PCGUARD instrumented binaries, it is much more difficult. Here you can either modify the `__sanitizer_cov_trace_pc_guard` function in `instrumentation/afl-llvm-rt.o.c` to write a backtrace to a file if the ID in `__afl_area_ptr[*guard]` is one of the unstable edge IDs. - (Example code is already there). - Then recompile and reinstall `llvm_mode` and rebuild your target. - Run the recompiled target with `afl-fuzz` for a while and then check the file that you wrote with the backtrace information. - Alternatively, you can use `gdb` to hook `__sanitizer_cov_trace_pc_guard_init` on start, check to which memory address the edge ID value is written, and set a write breakpoint to that address (`watch 0x.....`). - - c) In other instrumentation types, this is not possible. - So just recompile with the two mentioned above. - This is just for identifying the functions that have unstable edges. + a) For LTO instrumented binaries, this can be documented during compile + time, just set `export AFL_LLVM_DOCUMENT_IDS=/path/to/a/file`. This file + will have one assigned edge ID and the corresponding function per line. + + b) For PCGUARD instrumented binaries, it is much more difficult. Here you + can either modify the `__sanitizer_cov_trace_pc_guard` function in + `instrumentation/afl-llvm-rt.o.c` to write a backtrace to a file if the + ID in `__afl_area_ptr[*guard]` is one of the unstable edge IDs. (Example + code is already there). Then recompile and reinstall `llvm_mode` and + rebuild your target. Run the recompiled target with `afl-fuzz` for a + while and then check the file that you wrote with the backtrace + information. Alternatively, you can use `gdb` to hook + `__sanitizer_cov_trace_pc_guard_init` on start, check to which memory + address the edge ID value is written, and set a write breakpoint to that + address (`watch 0x.....`). + + c) In other instrumentation types, this is not possible. So just recompile + with the two mentioned above. This is just for identifying the functions + that have unstable edges. 2. Identify which edge ID numbers are unstable. Run the target with `export AFL_DEBUG=1` for a few minutes then terminate. The out/fuzzer_stats file will then show the edge IDs that were identified - as unstable in the `var_bytes` entry. You can match these numbers - directly to the data you created in the first step. - Now you know which functions are responsible for the instability + as unstable in the `var_bytes` entry. You can match these numbers directly + to the data you created in the first step. Now you know which functions are + responsible for the instability 3. Create a text file with the filenames/functions - Identify which source code files contain the functions that you need to remove from instrumentation, or just specify the functions you want to skip for instrumentation. - Note that optimization might inline functions! + Identify which source code files contain the functions that you need to + remove from instrumentation, or just specify the functions you want to skip + for instrumentation. Note that optimization might inline functions! + + Follow this document on how to do this: + [instrumentation/README.instrument_list.md](../instrumentation/README.instrument_list.md). - Follow this document on how to do this: [instrumentation/README.instrument_list.md](../instrumentation/README.instrument_list.md). If `PCGUARD` is used, then you need to follow this guide (needs llvm 12+!): [https://clang.llvm.org/docs/SanitizerCoverage.html#partially-disabling-instrumentation](https://clang.llvm.org/docs/SanitizerCoverage.html#partially-disabling-instrumentation) - Only exclude those functions from instrumentation that provide no value for coverage - that is if it does not process any fuzz data directly or indirectly (e.g. hash maps, thread management etc.). - If however a function directly or indirectly handles fuzz data, then you should not put the function in a deny instrumentation list and rather live with the instability it comes with. + Only exclude those functions from instrumentation that provide no value for + coverage - that is if it does not process any fuzz data directly or + indirectly (e.g., hash maps, thread management etc.). If, however, a + function directly or indirectly handles fuzz data, then you should not put + the function in a deny instrumentation list and rather live with the + instability it comes with. 4. Recompile the target Recompile, fuzz it, be happy :) - This link explains this process for [Fuzzbench](https://github.com/google/fuzzbench/issues/677). + This link explains this process for + [Fuzzbench](https://github.com/google/fuzzbench/issues/677).
\ No newline at end of file diff --git a/docs/custom_mutators.md b/docs/custom_mutators.md index b1dfd309..7b4e0516 100644 --- a/docs/custom_mutators.md +++ b/docs/custom_mutators.md @@ -1,16 +1,16 @@ # Custom Mutators in AFL++ This file describes how you can implement custom mutations to be used in AFL. -For now, we support C/C++ library and Python module, collectivelly named as the +For now, we support C/C++ library and Python module, collectively named as the custom mutator. -There is also experimental support for Rust in `custom_mutators/rust`. -Please refer to that directory for documentation. -Run ```cargo doc -p custom_mutator --open``` in that directory to view the -documentation in your web browser. +There is also experimental support for Rust in `custom_mutators/rust`. For +documentation, refer to that directory. Run `cargo doc -p custom_mutator --open` +in that directory to view the documentation in your web browser. Implemented by -- C/C++ library (`*.so`): Khaled Yakdan from Code Intelligence (<yakdan@code-intelligence.de>) +- C/C++ library (`*.so`): Khaled Yakdan from Code Intelligence + (<yakdan@code-intelligence.de>) - Python module: Christian Holler from Mozilla (<choller@mozilla.com>) ## 1) Introduction @@ -21,13 +21,17 @@ fuzzing by using libraries that perform mutations according to a given grammar. The custom mutator is passed to `afl-fuzz` via the `AFL_CUSTOM_MUTATOR_LIBRARY` or `AFL_PYTHON_MODULE` environment variable, and must export a fuzz function. -Now AFL also supports multiple custom mutators which can be specified in the same `AFL_CUSTOM_MUTATOR_LIBRARY` environment variable like this. +Now AFL++ also supports multiple custom mutators which can be specified in the +same `AFL_CUSTOM_MUTATOR_LIBRARY` environment variable like this. + ```bash export AFL_CUSTOM_MUTATOR_LIBRARY="full/path/to/mutator_first.so;full/path/to/mutator_second.so" ``` -Please see [APIs](#2-apis) and [Usage](#3-usage) for detail. -The custom mutation stage is set to be the first non-deterministic stage (right before the havoc stage). +For details, see [APIs](#2-apis) and [Usage](#3-usage). + +The custom mutation stage is set to be the first non-deterministic stage (right +before the havoc stage). Note: If `AFL_CUSTOM_MUTATOR_ONLY` is set, all mutations will solely be performed with the custom mutator. @@ -35,6 +39,7 @@ performed with the custom mutator. ## 2) APIs C/C++: + ```c void *afl_custom_init(afl_state_t *afl, unsigned int seed); unsigned int afl_custom_fuzz_count(void *data, const unsigned char *buf, size_t buf_size); @@ -53,6 +58,7 @@ void afl_custom_deinit(void *data); ``` Python: + ```python def init(seed): pass @@ -101,7 +107,8 @@ def deinit(): # optional for Python - `init`: - This method is called when AFL++ starts up and is used to seed RNG and set up buffers and state. + This method is called when AFL++ starts up and is used to seed RNG and set + up buffers and state. - `queue_get` (optional): @@ -110,27 +117,26 @@ def deinit(): # optional for Python - `fuzz_count` (optional): - When a queue entry is selected to be fuzzed, afl-fuzz selects the number - of fuzzing attempts with this input based on a few factors. - If however the custom mutator wants to set this number instead on how often - it is called for a specific queue entry, use this function. - This function is most useful if `AFL_CUSTOM_MUTATOR_ONLY` is **not** used. + When a queue entry is selected to be fuzzed, afl-fuzz selects the number of + fuzzing attempts with this input based on a few factors. If, however, the + custom mutator wants to set this number instead on how often it is called + for a specific queue entry, use this function. This function is most useful + if `AFL_CUSTOM_MUTATOR_ONLY` is **not** used. - `fuzz` (optional): This method performs custom mutations on a given input. It also accepts an - additional test case. - Note that this function is optional - but it makes sense to use it. - You would only skip this if `post_process` is used to fix checksums etc. - so if you are using it e.g. as a post processing library. + additional test case. Note that this function is optional - but it makes + sense to use it. You would only skip this if `post_process` is used to fix + checksums etc. so if you are using it, e.g., as a post processing library. Note that a length > 0 *must* be returned! - `describe` (optional): When this function is called, it shall describe the current test case, - generated by the last mutation. This will be called, for example, - to name the written test case file after a crash occurred. - Using it can help to reproduce crashing mutations. + generated by the last mutation. This will be called, for example, to name + the written test case file after a crash occurred. Using it can help to + reproduce crashing mutations. - `havoc_mutation` and `havoc_mutation_probability` (optional): @@ -142,21 +148,21 @@ def deinit(): # optional for Python - `post_process` (optional): For some cases, the format of the mutated data returned from the custom - mutator is not suitable to directly execute the target with this input. - For example, when using libprotobuf-mutator, the data returned is in a - protobuf format which corresponds to a given grammar. In order to execute - the target, the protobuf data must be converted to the plain-text format - expected by the target. In such scenarios, the user can define the - `post_process` function. This function is then transforming the data into the - format expected by the API before executing the target. + mutator is not suitable to directly execute the target with this input. For + example, when using libprotobuf-mutator, the data returned is in a protobuf + format which corresponds to a given grammar. In order to execute the target, + the protobuf data must be converted to the plain-text format expected by the + target. In such scenarios, the user can define the `post_process` function. + This function is then transforming the data into the format expected by the + API before executing the target. This can return any python object that implements the buffer protocol and supports PyBUF_SIMPLE. These include bytes, bytearray, etc. - `queue_new_entry` (optional): - This methods is called after adding a new test case to the queue. - If the contents of the file was changed return True, False otherwise. + This methods is called after adding a new test case to the queue. If the + contents of the file was changed, return True, False otherwise. - `introspection` (optional): @@ -168,8 +174,8 @@ def deinit(): # optional for Python The last method to be called, deinitializing the state. -Note that there are also three functions for trimming as described in the -next section. +Note that there are also three functions for trimming as described in the next +section. ### Trimming Support @@ -177,8 +183,8 @@ The generic trimming routines implemented in AFL++ can easily destroy the structure of complex formats, possibly leading to a point where you have a lot of test cases in the queue that your Python module cannot process anymore but your target application still accepts. This is especially the case when your -target can process a part of the input (causing coverage) and then errors out -on the remaining input. +target can process a part of the input (causing coverage) and then errors out on +the remaining input. In such cases, it makes sense to implement a custom trimming routine. The API consists of multiple methods because after each trimming step, we have to go @@ -189,8 +195,9 @@ trimmed input. Here's a quick API description: This method is called at the start of each trimming operation and receives the initial buffer. It should return the amount of iteration steps possible - on this input (e.g. if your input has n elements and you want to remove them - one by one, return n, if you do a binary search, return log(n), and so on). + on this input (e.g., if your input has n elements and you want to remove + them one by one, return n, if you do a binary search, return log(n), and so + on). If your trimming algorithm doesn't allow to determine the amount of (remaining) steps easily (esp. while running), then you can alternatively @@ -202,21 +209,21 @@ trimmed input. Here's a quick API description: - `trim` (optional) This method is called for each trimming operation. It doesn't have any - arguments because we already have the initial buffer from `init_trim` and we - can memorize the current state in the data variables. This can also save + arguments because there is already the initial buffer from `init_trim` and + we can memorize the current state in the data variables. This can also save reparsing steps for each iteration. It should return the trimmed input buffer. - `post_trim` (optional) This method is called after each trim operation to inform you if your - trimming step was successful or not (in terms of coverage). If you receive - a failure here, you should reset your input to the last known good state. - In any case, this method must return the next trim iteration index (from 0 - to the maximum amount of steps you returned in `init_trim`). + trimming step was successful or not (in terms of coverage). If you receive a + failure here, you should reset your input to the last known good state. In + any case, this method must return the next trim iteration index (from 0 to + the maximum amount of steps you returned in `init_trim`). Omitting any of three trimming methods will cause the trimming to be disabled -and trigger a fallback to the builtin default trimming routine. +and trigger a fallback to the built-in default trimming routine. ### Environment Variables @@ -224,11 +231,10 @@ Optionally, the following environment variables are supported: - `AFL_CUSTOM_MUTATOR_ONLY` - Disable all other mutation stages. This can prevent broken test cases - (those that your Python module can't work with anymore) to fill up your - queue. Best combined with a custom trimming routine (see below) because - trimming can cause the same test breakage like havoc and splice. - + Disable all other mutation stages. This can prevent broken test cases (those + that your Python module can't work with anymore) to fill up your queue. Best + combined with a custom trimming routine (see below) because trimming can + cause the same test breakage like havoc and splice. - `AFL_PYTHON_ONLY` @@ -264,22 +270,27 @@ In case your setup is different, set the necessary variables like this: ### Custom Mutator Preparation For C/C++ mutators, the source code must be compiled as a shared object: + ```bash gcc -shared -Wall -O3 example.c -o example.so ``` -Note that if you specify multiple custom mutators, the corresponding functions will -be called in the order in which they are specified. e.g first `post_process` function of -`example_first.so` will be called and then that of `example_second.so`. + +Note that if you specify multiple custom mutators, the corresponding functions +will be called in the order in which they are specified. E.g., the first +`post_process` function of `example_first.so` will be called and then that of +`example_second.so`. ### Run C/C++ + ```bash export AFL_CUSTOM_MUTATOR_LIBRARY="/full/path/to/example_first.so;/full/path/to/example_second.so" afl-fuzz /path/to/program ``` Python + ```bash export PYTHONPATH=`dirname /full/path/to/example.py` export AFL_PYTHON_MODULE=example @@ -288,8 +299,8 @@ afl-fuzz /path/to/program ## 4) Example -Please see [example.c](../custom_mutators/examples/example.c) and -[example.py](../custom_mutators/examples/example.py) +See [example.c](../custom_mutators/examples/example.c) and +[example.py](../custom_mutators/examples/example.py). ## 5) Other Resources @@ -297,4 +308,4 @@ Please see [example.c](../custom_mutators/examples/example.c) and - [bruce30262/libprotobuf-mutator_fuzzing_learning](https://github.com/bruce30262/libprotobuf-mutator_fuzzing_learning/tree/master/4_libprotobuf_aflpp_custom_mutator) - [thebabush/afl-libprotobuf-mutator](https://github.com/thebabush/afl-libprotobuf-mutator) - [XML Fuzzing@NullCon 2017](https://www.agarri.fr/docs/XML_Fuzzing-NullCon2017-PUBLIC.pdf) - - [A bug detected by AFL + XML-aware mutators](https://bugs.chromium.org/p/chromium/issues/detail?id=930663) + - [A bug detected by AFL + XML-aware mutators](https://bugs.chromium.org/p/chromium/issues/detail?id=930663)
\ No newline at end of file diff --git a/docs/env_variables.md b/docs/env_variables.md index c1c70ec5..c45f4ab9 100644 --- a/docs/env_variables.md +++ b/docs/env_variables.md @@ -59,9 +59,9 @@ fairly broad use of environment variables instead: otherwise. - By default, the wrapper appends `-O3` to optimize builds. Very rarely, this - will cause problems in programs built with -Werror, simply because `-O3` - enables more thorough code analysis and can spew out additional warnings. To - disable optimizations, set `AFL_DONT_OPTIMIZE`. However, if `-O...` and/or + will cause problems in programs built with -Werror, because `-O3` enables + more thorough code analysis and can spew out additional warnings. To disable + optimizations, set `AFL_DONT_OPTIMIZE`. However, if `-O...` and/or `-fno-unroll-loops` are set, these are not overridden. - Setting `AFL_HARDEN` automatically adds code hardening options when invoking @@ -80,9 +80,9 @@ fairly broad use of environment variables instead: Setting `AFL_INST_RATIO` to 0 is a valid choice. This will instrument only the transitions between function entry points, but not individual branches. - Note that this is an outdated variable. A few instances (e.g. afl-gcc) still - support these, but state-of-the-art (e.g. LLVM LTO and LLVM PCGUARD) do not - need this. + Note that this is an outdated variable. A few instances (e.g., afl-gcc) + still support these, but state-of-the-art (e.g., LLVM LTO and LLVM PCGUARD) + do not need this. - `AFL_NO_BUILTIN` causes the compiler to generate code suitable for use with libtokencap.so (but perhaps running a bit slower than without the flag). @@ -109,7 +109,7 @@ fairly broad use of environment variables instead: - `AFL_USE_MSAN=1` - activates the memory sanitizer (uninitialized memory) - `AFL_USE_TSAN=1` - activates the thread sanitizer to find thread race conditions - - `AFL_USE_UBSAN=1` - activates the undefined behaviour sanitizer + - `AFL_USE_UBSAN=1` - activates the undefined behavior sanitizer - `TMPDIR` is used by afl-as for temporary files; if this variable is not set, the tool defaults to /tmp. @@ -307,7 +307,7 @@ checks or alter some of the more exotic semantics of the tool: (`-i in`). This is an important feature to set when resuming a fuzzing session. - - Setting `AFL_CRASH_EXITCODE` sets the exit code AFL treats as crash. For + - Setting `AFL_CRASH_EXITCODE` sets the exit code AFL++ treats as crash. For example, if `AFL_CRASH_EXITCODE='-1'` is set, each input resulting in a `-1` return code (i.e. `exit(-1)` got called), will be treated as if a crash had occurred. This may be beneficial if you look for higher-level faulty @@ -319,8 +319,8 @@ checks or alter some of the more exotic semantics of the tool: afl-fuzz), setting `AFL_PYTHON_MODULE` to a Python module can also provide additional mutations. If `AFL_CUSTOM_MUTATOR_ONLY` is also set, all mutations will solely be performed with the custom mutator. This feature - allows to configure custom mutators which can be very helpful, e.g. fuzzing - XML or other highly flexible structured input. Please see + allows to configure custom mutators which can be very helpful, e.g., fuzzing + XML or other highly flexible structured input. For details, see [custom_mutators.md](custom_mutators.md). - Setting `AFL_CYCLE_SCHEDULES` will switch to a different schedule every time @@ -336,7 +336,7 @@ checks or alter some of the more exotic semantics of the tool: - Setting `AFL_DISABLE_TRIM` tells afl-fuzz not to trim test cases. This is usually a bad idea! - - `AFL_EXIT_ON_SEED_ISSUES` will restore the vanilla afl-fuzz behaviour which + - `AFL_EXIT_ON_SEED_ISSUES` will restore the vanilla afl-fuzz behavior which does not allow crashes or timeout seeds in the initial -i corpus. - `AFL_EXIT_ON_TIME` causes afl-fuzz to terminate if no new paths were found @@ -449,7 +449,7 @@ checks or alter some of the more exotic semantics of the tool: not crash the target again when the test case is given. To be able to still re-trigger these crashes, you can use the `AFL_PERSISTENT_RECORD` variable with a value of how many previous fuzz cases to keep prio a crash. If set to - e.g. 10, then the 9 previous inputs are written to out/default/crashes as + e.g., 10, then the 9 previous inputs are written to out/default/crashes as RECORD:000000,cnt:000000 to RECORD:000000,cnt:000008 and RECORD:000000,cnt:000009 being the crash case. NOTE: This option needs to be enabled in config.h first! @@ -493,7 +493,7 @@ checks or alter some of the more exotic semantics of the tool: This is especially useful when running multiple instances (`-M/-S` for example). Applied tags are `banner` and `afl_version`. `banner` corresponds to the name of the fuzzer provided through `-M/-S`. `afl_version` - corresponds to the currently running AFL version (e.g. `++3.0c`). Default + corresponds to the currently running AFL++ version (e.g., `++3.0c`). Default (empty/non present) will add no tags to the metrics. For more information, see [rpc_statsd.md](rpc_statsd.md). @@ -535,11 +535,11 @@ The QEMU wrapper used to instrument binary-only code supports several settings: - `AFL_DEBUG` will print the found entry point for the binary to stderr. Use this if you are unsure if the entry point might be wrong - but use it - directly, e.g. `afl-qemu-trace ./program`. + directly, e.g., `afl-qemu-trace ./program`. - `AFL_ENTRYPOINT` allows you to specify a specific entry point into the binary (this can be very good for the performance!). The entry point is - specified as hex address, e.g. `0x4004110`. Note that the address must be + specified as hex address, e.g., `0x4004110`. Note that the address must be the address of a basic block. - Setting `AFL_INST_LIBS` causes the translator to also instrument the code @@ -553,26 +553,26 @@ The QEMU wrapper used to instrument binary-only code supports several settings: and sub in x86 and x86_64. This is an alias of `AFL_COMPCOV_LEVEL=1` when `AFL_COMPCOV_LEVEL` is not specified. - - With `AFL_QEMU_FORCE_DFL` you force QEMU to ignore the registered signal + - With `AFL_QEMU_FORCE_DFL`, you force QEMU to ignore the registered signal handlers of the target. - When the target is i386/x86_64, you can specify the address of the function that has to be the body of the persistent loop using `AFL_QEMU_PERSISTENT_ADDR=start addr`. - - With `AFL_QEMU_PERSISTENT_GPR=1` QEMU will save the original value of + - With `AFL_QEMU_PERSISTENT_GPR=1`, QEMU will save the original value of general purpose registers and restore them in each persistent cycle. - Another modality to execute the persistent loop is to specify also the - `AFL_QEMU_PERSISTENT_RET=end addr` env variable. With this variable + `AFL_QEMU_PERSISTENT_RET=end addr` environment variable. With this variable assigned, instead of patching the return address, the specified instruction is transformed to a jump towards `start addr`. - - With `AFL_QEMU_PERSISTENT_RETADDR_OFFSET` you can specify the offset from + - With `AFL_QEMU_PERSISTENT_RETADDR_OFFSET`, you can specify the offset from the stack pointer in which QEMU can find the return address when `start addr` is hit. - - With `AFL_USE_QASAN` you can enable QEMU AddressSanitizer for dynamically + - With `AFL_USE_QASAN`, you can enable QEMU AddressSanitizer for dynamically linked binaries. - The underlying QEMU binary will recognize any standard "user space @@ -583,86 +583,89 @@ The QEMU wrapper used to instrument binary-only code supports several settings: The FRIDA wrapper used to instrument binary-only code supports many of the same options as `afl-qemu-trace`, but also has a number of additional advanced -options. These are listed in brief below (see [here](../frida_mode/README.md) -for more details). These settings are provided for compatibiltiy with QEMU mode, -the preferred way to configure FRIDA mode is through its -[scripting](../frida_mode/Scripting.md) support. +options. These are listed in brief below (see +[frida_mode/README.md](../frida_mode/README.md) for more details). These +settings are provided for compatibility with QEMU mode, the preferred way to +configure FRIDA mode is through its [scripting](../frida_mode/Scripting.md) +support. * `AFL_FRIDA_DEBUG_MAPS` - See `AFL_QEMU_DEBUG_MAPS` * `AFL_FRIDA_DRIVER_NO_HOOK` - See `AFL_QEMU_DRIVER_NO_HOOK`. When using the -QEMU driver to provide a `main` loop for a user provided -`LLVMFuzzerTestOneInput`, this option configures the driver to read input from -`stdin` rather than using in-memory test cases. + QEMU driver to provide a `main` loop for a user provided + `LLVMFuzzerTestOneInput`, this option configures the driver to read input from + `stdin` rather than using in-memory test cases. * `AFL_FRIDA_EXCLUDE_RANGES` - See `AFL_QEMU_EXCLUDE_RANGES` * `AFL_FRIDA_INST_COVERAGE_FILE` - File to write DynamoRio format coverage -information (e.g. to be loaded within IDA lighthouse). + information (e.g., to be loaded within IDA lighthouse). * `AFL_FRIDA_INST_DEBUG_FILE` - File to write raw assembly of original blocks -and their instrumented counterparts during block compilation. + and their instrumented counterparts during block compilation. * `AFL_FRIDA_INST_JIT` - Enable the instrumentation of Just-In-Time compiled -code. Code is considered to be JIT if the executable segment is not backed by a -file. + code. Code is considered to be JIT if the executable segment is not backed by + a file. * `AFL_FRIDA_INST_NO_OPTIMIZE` - Don't use optimized inline assembly coverage -instrumentation (the default where available). Required to use -`AFL_FRIDA_INST_TRACE`. + instrumentation (the default where available). Required to use + `AFL_FRIDA_INST_TRACE`. * `AFL_FRIDA_INST_NO_BACKPATCH` - Disable backpatching. At the end of executing -each block, control will return to FRIDA to identify the next block to execute. -* `AFL_FRIDA_INST_NO_PREFETCH` - Disable prefetching. By default the child will -report instrumented blocks back to the parent so that it can also instrument -them and they be inherited by the next child on fork, implies -`AFL_FRIDA_INST_NO_PREFETCH_BACKPATCH`. + each block, control will return to FRIDA to identify the next block to + execute. +* `AFL_FRIDA_INST_NO_PREFETCH` - Disable prefetching. By default, the child will + report instrumented blocks back to the parent so that it can also instrument + them and they be inherited by the next child on fork, implies + `AFL_FRIDA_INST_NO_PREFETCH_BACKPATCH`. * `AFL_FRIDA_INST_NO_PREFETCH_BACKPATCH` - Disable prefetching of stalker -backpatching information. By default the child will report applied backpatches -to the parent so that they can be applied and then be inherited by the next -child on fork. + backpatching information. By default, the child will report applied + backpatches to the parent so that they can be applied and then be inherited by + the next child on fork. * `AFL_FRIDA_INST_RANGES` - See `AFL_QEMU_INST_RANGES` * `AFL_FRIDA_INST_SEED` - Sets the initial seed for the hash function used to -generate block (and hence edge) IDs. Setting this to a constant value may be -useful for debugging purposes, e.g. investigating unstable edges. -* `AFL_FRIDA_INST_TRACE` - Log to stdout the address of executed blocks, -implies `AFL_FRIDA_INST_NO_OPTIMIZE`. + generate block (and hence edge) IDs. Setting this to a constant value may be + useful for debugging purposes, e.g., investigating unstable edges. +* `AFL_FRIDA_INST_TRACE` - Log to stdout the address of executed blocks, implies + `AFL_FRIDA_INST_NO_OPTIMIZE`. * `AFL_FRIDA_INST_TRACE_UNIQUE` - As per `AFL_FRIDA_INST_TRACE`, but each edge -is logged only once, requires `AFL_FRIDA_INST_NO_OPTIMIZE`. + is logged only once, requires `AFL_FRIDA_INST_NO_OPTIMIZE`. * `AFL_FRIDA_INST_UNSTABLE_COVERAGE_FILE` - File to write DynamoRio format -coverage information for unstable edges (e.g. to be loaded within IDA -lighthouse). + coverage information for unstable edges (e.g., to be loaded within IDA + lighthouse). * `AFL_FRIDA_JS_SCRIPT` - Set the script to be loaded by the FRIDA scripting -engine. See [here](Scripting.md) for details. + engine. See [frida_mode/Scripting.md](../frida_mode/Scripting.md) for details. * `AFL_FRIDA_OUTPUT_STDOUT` - Redirect the standard output of the target -application to the named file (supersedes the setting of `AFL_DEBUG_CHILD`) + application to the named file (supersedes the setting of `AFL_DEBUG_CHILD`) * `AFL_FRIDA_OUTPUT_STDERR` - Redirect the standard error of the target -application to the named file (supersedes the setting of `AFL_DEBUG_CHILD`) + application to the named file (supersedes the setting of `AFL_DEBUG_CHILD`) * `AFL_FRIDA_PERSISTENT_ADDR` - See `AFL_QEMU_PERSISTENT_ADDR` * `AFL_FRIDA_PERSISTENT_CNT` - See `AFL_QEMU_PERSISTENT_CNT` * `AFL_FRIDA_PERSISTENT_DEBUG` - Insert a Breakpoint into the instrumented code -at `AFL_FRIDA_PERSISTENT_HOOK` and `AFL_FRIDA_PERSISTENT_RET` to allow the user -to detect issues in the persistent loop using a debugger. + at `AFL_FRIDA_PERSISTENT_HOOK` and `AFL_FRIDA_PERSISTENT_RET` to allow the + user to detect issues in the persistent loop using a debugger. * `AFL_FRIDA_PERSISTENT_HOOK` - See `AFL_QEMU_PERSISTENT_HOOK` * `AFL_FRIDA_PERSISTENT_RET` - See `AFL_QEMU_PERSISTENT_RET` * `AFL_FRIDA_SECCOMP_FILE` - Write a log of any syscalls made by the target to -the specified file. + the specified file. * `AFL_FRIDA_STALKER_ADJACENT_BLOCKS` - Configure the number of adjacent blocks - to fetch when generating instrumented code. By fetching blocks in the same - order they appear in the original program, rather than the order of execution - should help reduce locallity and adjacency. This includes allowing us to vector - between adjancent blocks using a NOP slide rather than an immediate branch. + to fetch when generating instrumented code. By fetching blocks in the same + order they appear in the original program, rather than the order of execution + should help reduce locallity and adjacency. This includes allowing us to + vector between adjancent blocks using a NOP slide rather than an immediate + branch. * `AFL_FRIDA_STALKER_IC_ENTRIES` - Configure the number of inline cache entries -stored along-side branch instructions which provide a cache to avoid having to -call back into FRIDA to find the next block. Default is 32. + stored along-side branch instructions which provide a cache to avoid having to + call back into FRIDA to find the next block. Default is 32. * `AFL_FRIDA_STATS_FILE` - Write statistics information about the code being -instrumented to the given file name. The statistics are written only for the -child process when new block is instrumented (when the -`AFL_FRIDA_STATS_INTERVAL` has expired). Note that simply because a new path is -found does not mean a new block needs to be compiled. It could simply be that -the existing blocks instrumented have been executed in a different order. + instrumented to the given file name. The statistics are written only for the + child process when new block is instrumented (when the + `AFL_FRIDA_STATS_INTERVAL` has expired). Note that just because a new path is + found does not mean a new block needs to be compiled. It could be that the + existing blocks instrumented have been executed in a different order. * `AFL_FRIDA_STATS_INTERVAL` - The maximum frequency to output statistics -information. Stats will be written whenever they are updated if the given -interval has elapsed since last time they were written. + information. Stats will be written whenever they are updated if the given + interval has elapsed since last time they were written. * `AFL_FRIDA_TRACEABLE` - Set the child process to be traceable by any process -to aid debugging and overcome the restrictions imposed by YAMA. Supported on -Linux only. Permits a non-root user to use `gcore` or similar to collect a core -dump of the instrumented target. Note that in order to capture the core dump you -must set a sufficient timeout (using `-t`) to avoid `afl-fuzz` killing the -process whilst it is being dumped. + to aid debugging and overcome the restrictions imposed by YAMA. Supported on + Linux only. Permits a non-root user to use `gcore` or similar to collect a + core dump of the instrumented target. Note that in order to capture the core + dump you must set a sufficient timeout (using `-t`) to avoid `afl-fuzz` + killing the process whilst it is being dumped. ## 8) Settings for afl-cmin diff --git a/docs/features.md b/docs/features.md index 35a869a9..431d9eb1 100644 --- a/docs/features.md +++ b/docs/features.md @@ -1,10 +1,10 @@ # Important features of AFL++ AFL++ supports llvm from 3.8 up to version 12, very fast binary fuzzing with -QEMU 5.1 with laf-intel and redqueen, frida mode, unicorn mode, gcc plugin, full +QEMU 5.1 with laf-intel and redqueen, FRIDA mode, unicorn mode, gcc plugin, full *BSD, Mac OS, Solaris and Android support and much, much, much more. -| Feature/Instrumentation | afl-gcc | llvm | gcc_plugin | frida_mode(9) | qemu_mode(10) |unicorn_mode(10) |coresight_mode(11)| +| Feature/Instrumentation | afl-gcc | llvm | gcc_plugin | FRIDA mode(9) | QEMU mode(10) |unicorn_mode(10) |coresight_mode(11)| | -------------------------|:-------:|:---------:|:----------:|:----------------:|:----------------:|:----------------:|:----------------:| | Threadsafe counters | | x(3) | | | | | | | NeverZero | x86[_64]| x(1) | x | x | x | x | | @@ -19,8 +19,8 @@ QEMU 5.1 with laf-intel and redqueen, frida mode, unicorn mode, gcc plugin, full | Snapshot LKM Support | | (x)(8) | (x)(8) | | (x)(5) | | | | Shared Memory Test cases | | x | x | x86[_64]/arm64 | x | x | | -1. default for LLVM >= 9.0, env var for older version due an efficiency bug in - previous llvm versions +1. default for LLVM >= 9.0, environment variable for older version due an + efficiency bug in previous llvm versions 2. GCC creates non-performant code, hence it is disabled in gcc_plugin 3. with `AFL_LLVM_THREADSAFE_INST`, disables NeverZero 4. with pcguard mode and LTO mode for LLVM 11 and newer @@ -30,16 +30,16 @@ QEMU 5.1 with laf-intel and redqueen, frida mode, unicorn mode, gcc plugin, full versions that write to a file to use with afl-fuzz' `-x` 8. the snapshot LKM is currently unmaintained due to too many kernel changes coming too fast :-( -9. frida mode is supported on Linux and MacOS for Intel and ARM +9. FRIDA mode is supported on Linux and MacOS for Intel and ARM 10. QEMU/Unicorn is only supported on Linux 11. Coresight mode is only available on AARCH64 Linux with a CPU with Coresight extension Among others, the following features and patches have been integrated: -* NeverZero patch for afl-gcc, instrumentation, qemu_mode and unicorn_mode which +* NeverZero patch for afl-gcc, instrumentation, QEMU mode and unicorn_mode which prevents a wrapping map value to zero, increases coverage -* Persistent mode, deferred forkserver and in-memory fuzzing for qemu_mode +* Persistent mode, deferred forkserver and in-memory fuzzing for QEMU mode * Unicorn mode which allows fuzzing of binaries from completely different platforms (integration provided by domenukk) * The new CmpLog instrumentation for LLVM and QEMU inspired by @@ -51,7 +51,7 @@ Among others, the following features and patches have been integrated: [https://github.com/puppet-meteor/MOpt-AFL](https://github.com/puppet-meteor/MOpt-AFL) * LLVM mode Ngram coverage by Adrian Herrera [https://github.com/adrianherrera/afl-ngram-pass](https://github.com/adrianherrera/afl-ngram-pass) -* LAF-Intel/CompCov support for instrumentation, qemu_mode and unicorn_mode +* LAF-Intel/CompCov support for instrumentation, QEMU mode and unicorn_mode (with enhanced capabilities) * Radamsa and honggfuzz mutators (as custom mutators). * QBDI mode to fuzz android native libraries via Quarkslab's diff --git a/docs/fuzzing_binary-only_targets.md b/docs/fuzzing_binary-only_targets.md index 290c9bec..5434a22c 100644 --- a/docs/fuzzing_binary-only_targets.md +++ b/docs/fuzzing_binary-only_targets.md @@ -12,18 +12,19 @@ fuzzed with AFL++. ## TL;DR: -Qemu_mode in persistent mode is the fastest - if the stability is high enough. +QEMU mode in persistent mode is the fastest - if the stability is high enough. Otherwise, try RetroWrite, Dyninst, and if these fail, too, then try standard -qemu_mode with AFL_ENTRYPOINT to where you need it. +QEMU mode with `AFL_ENTRYPOINT` to where you need it. -If your target is a library, then use frida_mode. +If your target is a library, then use FRIDA mode. If your target is non-linux, then use unicorn_mode. ## Fuzzing binary-only targets with AFL++ -### Qemu_mode -Qemu_mode is the "native" solution to the program. It is available in the +### QEMU mode + +QEMU mode is the "native" solution to the program. It is available in the ./qemu_mode/ directory and, once compiled, it can be accessed by the afl-fuzz -Q command line option. It is the easiest to use alternative and even works for cross-platform binaries. @@ -37,11 +38,12 @@ cd qemu_mode ./build_qemu_support.sh ``` -The following setup to use qemu_mode is recommended: +The following setup to use QEMU mode is recommended: + * run 1 afl-fuzz -Q instance with CMPLOG (`-c 0` + `AFL_COMPCOV_LEVEL=2`) * run 1 afl-fuzz -Q instance with QASAN (`AFL_USE_QASAN=1`) * run 1 afl-fuzz -Q instance with LAF (`AFL_PRELOAD=libcmpcov.so` + - `AFL_COMPCOV_LEVEL=2`), alternatively you can use frida_mode, just switch `-Q` + `AFL_COMPCOV_LEVEL=2`), alternatively you can use FRIDA mode, just switch `-Q` with `-O` and remove the LAF instance Then run as many instances as you have cores left with either -Q mode or - even @@ -49,16 +51,16 @@ better - use a binary rewriter like Dyninst, RetroWrite, ZAFL, etc. If [afl-dyninst](https://github.com/vanhauser-thc/afl-dyninst) works for your binary, then you can use afl-fuzz normally and it will have twice the speed -compared to qemu_mode (but slower than qemu persistent mode). Note that several +compared to QEMU mode (but slower than QEMU persistent mode). Note that several other binary rewriters exist, all with their advantages and caveats. -The speed decrease of qemu_mode is at about 50%. However, various options exist +The speed decrease of QEMU mode is at about 50%. However, various options exist to increase the speed: - using AFL_ENTRYPOINT to move the forkserver entry to a later basic block in the binary (+5-10% speed) - using persistent mode [qemu_mode/README.persistent.md](../qemu_mode/README.persistent.md) this will - result in a 150-300% overall speed increase - so 3-8x the original qemu_mode + result in a 150-300% overall speed increase - so 3-8x the original QEMU mode speed! - using AFL_CODE_START/AFL_CODE_END to only instrument specific parts @@ -71,7 +73,7 @@ conducive to parallelization. Note that there is also honggfuzz: [https://github.com/google/honggfuzz](https://github.com/google/honggfuzz) which -now has a qemu_mode, but its performance is just 1.5% ... +now has a QEMU mode, but its performance is just 1.5% ... If you like to code a customized fuzzer without much work, we highly recommend to check out our sister project libafl which supports QEMU, too: @@ -84,16 +86,17 @@ Wine, python3, and the pefile python package installed. It is included in AFL++. -For more information, see [qemu_mode/README.wine.md](../qemu_mode/README.wine.md). +For more information, see +[qemu_mode/README.wine.md](../qemu_mode/README.wine.md). -### Frida_mode +### FRIDA mode -In frida_mode, you can fuzz binary-only targets as easily as with QEMU. -Frida_mode is sometimes faster and sometimes slower than Qemu_mode. It is also +In FRIDA mode, you can fuzz binary-only targets as easily as with QEMU mode. +FRIDA mode is sometimes faster and sometimes slower than QEMU mode. It is also newer, lacks COMPCOV, and has the advantage that it works on MacOS (both intel and M1). -To build frida_mode: +To build FRIDA mode: ```shell cd frida_mode @@ -104,16 +107,16 @@ For additional instructions and caveats, see [frida_mode/README.md](../frida_mode/README.md). If possible, you should use the persistent mode, see -[qemu_frida/README.md](../qemu_frida/README.md). The mode is approximately 2-5x -slower than compile-time instrumentation, and is less conducive to -parallelization. But for binary-only fuzzing, it gives a huge speed improvement -if it is possible to use. +[instrumentation/README.persistent_mode.md](../instrumentation/README.persistent_mode.md). +The mode is approximately 2-5x slower than compile-time instrumentation, and is +less conducive to parallelization. But for binary-only fuzzing, it gives a huge +speed improvement if it is possible to use. If you want to fuzz a binary-only library, then you can fuzz it with frida-gum via frida_mode/. You will have to write a harness to call the target function in the library, use afl-frida.c as a template. -You can also perform remote fuzzing with frida, e.g. if you want to fuzz on +You can also perform remote fuzzing with frida, e.g., if you want to fuzz on iPhone or Android devices, for this you can use [https://github.com/ttdennis/fpicker/](https://github.com/ttdennis/fpicker/) as an intermediate that uses AFL++ for fuzzing. @@ -129,8 +132,7 @@ Unicorn is a fork of QEMU. The instrumentation is, therefore, very similar. In contrast to QEMU, Unicorn does not offer a full system or even userland emulation. Runtime environment and/or loaders have to be written from scratch, if needed. On top, block chaining has been removed. This means the speed boost -introduced in the patched QEMU Mode of AFL++ cannot simply be ported over to -Unicorn. +introduced in the patched QEMU Mode of AFL++ cannot be ported over to Unicorn. For non-Linux binaries, you can use AFL++'s unicorn_mode which can emulate anything you want - for the price of speed and user written scripts. @@ -149,11 +151,11 @@ For further information, check out If the goal is to fuzz a dynamic library, then there are two options available. For both, you need to write a small harness that loads and calls the library. -Then you fuzz this with either frida_mode or qemu_mode and either use +Then you fuzz this with either FRIDA mode or QEMU mode and either use `AFL_INST_LIBS=1` or `AFL_QEMU/FRIDA_INST_RANGES`. Another, less precise and slower option is to fuzz it with utils/afl_untracer/ -and use afl-untracer.c as a template. It is slower than frida_mode. +and use afl-untracer.c as a template. It is slower than FRIDA mode. For more information, see [utils/afl_untracer/README.md](../utils/afl_untracer/README.md). @@ -170,9 +172,11 @@ Fore more information, see ## Binary rewriters -An alternative solution are binary rewriters. They are faster then the solutions native to AFL++ but don't always work. +An alternative solution are binary rewriters. They are faster than the solutions +native to AFL++ but don't always work. ### ZAFL + ZAFL is a static rewriting platform supporting x86-64 C/C++, stripped/unstripped, and PIE/non-PIE binaries. Beyond conventional instrumentation, ZAFL's API enables transformation passes (e.g., laf-Intel, @@ -199,13 +203,13 @@ It is at about 80-85% performance. Dyninst is a binary instrumentation framework similar to Pintool and DynamoRIO. However, whereas Pintool and DynamoRIO work at runtime, Dyninst instruments the target at load time and then let it run - or save the binary with the changes. -This is great for some things, e.g. fuzzing, and not so effective for others, -e.g. malware analysis. +This is great for some things, e.g., fuzzing, and not so effective for others, +e.g., malware analysis. -So, what we can do with Dyninst is taking every basic block and put AFL++'s -instrumentation code in there - and then save the binary. Afterwards, we can -just fuzz the newly saved target binary with afl-fuzz. Sounds great? It is. The -issue though - it is a non-trivial problem to insert instructions, which change +So, what you can do with Dyninst is taking every basic block and putting AFL++'s +instrumentation code in there - and then save the binary. Afterwards, just fuzz +the newly saved target binary with afl-fuzz. Sounds great? It is. The issue +though - it is a non-trivial problem to insert instructions, which change addresses in the process space, so that everything is still working afterwards. Hence, more often than not binaries crash when they are run. @@ -275,7 +279,6 @@ There are many binary-only fuzzing frameworks. Some are great for CTFs but don't work with large binaries, others are very slow but have good path discovery, some are very hard to set-up... - * Jackalope: [https://github.com/googleprojectzero/Jackalope](https://github.com/googleprojectzero/Jackalope) * Manticore: diff --git a/docs/fuzzing_in_depth.md b/docs/fuzzing_in_depth.md index 251bbc1d..aaceb600 100644 --- a/docs/fuzzing_in_depth.md +++ b/docs/fuzzing_in_depth.md @@ -1,7 +1,7 @@ # Fuzzing with AFL++ The following describes how to fuzz with a target if source code is available. -If you have a binary-only target, please go to +If you have a binary-only target, go to [fuzzing_binary-only_targets.md](fuzzing_binary-only_targets.md). Fuzzing source code is a three-step process: @@ -106,9 +106,9 @@ You can select the mode for the afl-cc compiler by: MODE can be one of: LTO (afl-clang-lto*), LLVM (afl-clang-fast*), GCC_PLUGIN (afl-g*-fast) or GCC (afl-gcc/afl-g++) or CLANG(afl-clang/afl-clang++). -Because no AFL specific command-line options are accepted (beside the --afl-MODE -command), the compile-time tools make fairly broad use of environment variables, -which can be listed with `afl-cc -hh` or by reading +Because no AFL++ specific command-line options are accepted (beside the +--afl-MODE command), the compile-time tools make fairly broad use of environment +variables, which can be listed with `afl-cc -hh` or by reading [env_variables.md](env_variables.md). ### b) Selecting instrumentation options @@ -131,8 +131,8 @@ The following options are available when you instrument with LTO mode have to compile the target twice, once specifically with/for this mode by setting `AFL_LLVM_CMPLOG=1`, and pass this binary to afl-fuzz via the `-c` parameter. Note that you can compile also just a cmplog binary and use that - for both however there will be a performance penality. You can read more about - this in + for both, however, there will be a performance penalty. You can read more + about this in [instrumentation/README.cmplog.md](../instrumentation/README.cmplog.md). If you use LTO, LLVM or GCC_PLUGIN mode @@ -151,14 +151,14 @@ only instrument parts of the target that you are interested in: inlined and then would not match! See [instrumentation/README.instrument_list.md](../instrumentation/README.instrument_list.md) -There are many more options and modes available however these are most of the +There are many more options and modes available, however, these are most of the time less effective. See: -* [instrumentation/README.ctx.md](../instrumentation/README.ctx.md) -* [instrumentation/README.ngram.md](../instrumentation/README.ngram.md) +* [instrumentation/README.llvm.md#6) AFL++ Context Sensitive Branch Coverage](../instrumentation/README.llvm.md#6-afl-context-sensitive-branch-coverage) +* [instrumentation/README.llvm.md#7) AFL++ N-Gram Branch Coverage](../instrumentation/README.llvm.md#7-afl-n-gram-branch-coverage) AFL++ performs "never zero" counting in its bitmap. You can read more about this here: -* [instrumentation/README.neverzero.md](../instrumentation/README.neverzero.md) +* [instrumentation/README.llvm.md#8-neverzero-counters](../instrumentation/README.llvm.md#8-neverzero-counters) ### c) Selecting sanitizers @@ -167,7 +167,7 @@ allows you to find bugs that would not necessarily result in a crash. Note that sanitizers have a huge impact on CPU (= less executions per second) and RAM usage. Also you should only run one afl-fuzz instance per sanitizer -type. This is enough because a use-after-free bug will be picked up, e.g. by +type. This is enough because a use-after-free bug will be picked up, e.g., by ASAN (address sanitizer) anyway when syncing to other fuzzing instances, so not all fuzzing instances need to be instrumented with ASAN. @@ -175,11 +175,11 @@ The following sanitizers have built-in support in AFL++: * ASAN = Address SANitizer, finds memory corruption vulnerabilities like use-after-free, NULL pointer dereference, buffer overruns, etc. Enabled with `export AFL_USE_ASAN=1` before compiling. -* MSAN = Memory SANitizer, finds read access to uninitialized memory, eg. a +* MSAN = Memory SANitizer, finds read access to uninitialized memory, e.g., a local variable that is defined and read before it is even set. Enabled with `export AFL_USE_MSAN=1` before compiling. -* UBSAN = Undefined Behaviour SANitizer, finds instances where - by the C and - C++ standards - undefined behaviour happens, e.g. adding two signed integers +* UBSAN = Undefined Behavior SANitizer, finds instances where - by the C and C++ + standards - undefined behavior happens, e.g., adding two signed integers together where the result is larger than a signed integer can hold. Enabled with `export AFL_USE_UBSAN=1` before compiling. * CFISAN = Control Flow Integrity SANitizer, finds instances where the control @@ -196,24 +196,24 @@ The following sanitizers have built-in support in AFL++: of the target source code where you find a leak check necessary! Enabled with `export AFL_USE_LSAN=1` before compiling. -It is possible to further modify the behaviour of the sanitizers at run-time by +It is possible to further modify the behavior of the sanitizers at run-time by setting `ASAN_OPTIONS=...`, `LSAN_OPTIONS` etc. - the available parameters can be looked up in the sanitizer documentation of llvm/clang. afl-fuzz, however, requires some specific parameters important for fuzzing to be set. If you want to set your own, it might bail and report what it is missing. -Note that some sanitizers cannot be used together, e.g. ASAN and MSAN, and -others often cannot work together because of target weirdness, e.g. ASAN and +Note that some sanitizers cannot be used together, e.g., ASAN and MSAN, and +others often cannot work together because of target weirdness, e.g., ASAN and CFISAN. You might need to experiment which sanitizers you can combine in a target (which means more instances can be run without a sanitized target, which is more effective). ### d) Modifying the target -If the target has features that make fuzzing more difficult, e.g. checksums, -HMAC, etc. then modify the source code so that checks for these values are +If the target has features that make fuzzing more difficult, e.g., checksums, +HMAC, etc., then modify the source code so that checks for these values are removed. This can even be done safely for source code used in operational -products by eliminating these checks within these AFL specific blocks: +products by eliminating these checks within these AFL++ specific blocks: ``` #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION @@ -244,21 +244,22 @@ Then build the target. (Usually with `make`) **NOTES** -1. sometimes configure and build systems are fickle and do not like stderr +1. Sometimes configure and build systems are fickle and do not like stderr output (and think this means a test failure) - which is something AFL++ likes to do to show statistics. It is recommended to disable AFL++ instrumentation reporting via `export AFL_QUIET=1`. -2. sometimes configure and build systems error on warnings - these should be - disabled (e.g. `--disable-werror` for some configure scripts). +2. Sometimes configure and build systems error on warnings - these should be + disabled (e.g., `--disable-werror` for some configure scripts). -3. in case the configure/build system complains about AFL++'s compiler and - aborts then set `export AFL_NOOPT=1` which will then just behave like the +3. In case the configure/build system complains about AFL++'s compiler and + aborts, then set `export AFL_NOOPT=1` which will then just behave like the real compiler. This option has to be unset again before building the target! #### configure For `configure` build systems this is usually done by: + `CC=afl-clang-fast CXX=afl-clang-fast++ ./configure --disable-shared` Note that if you are using the (better) afl-clang-lto compiler you also have to @@ -268,6 +269,7 @@ described in [instrumentation/README.lto.md](../instrumentation/README.lto.md). #### cmake For `cmake` build systems this is usually done by: + `mkdir build; cd build; cmake -DCMAKE_C_COMPILER=afl-cc -DCMAKE_CXX_COMPILER=afl-c++ ..` Note that if you are using the (better) afl-clang-lto compiler you also have to @@ -302,13 +304,13 @@ that you want to fuzz, plus a few specific AFL++ functions around it. See [instrumentation/README.persistent_mode.md](../instrumentation/README.persistent_mode.md) for details. -Basically if you do not fuzz a target in persistent mode then you are just doing -it for a hobby and not professionally :-). +Basically if you do not fuzz a target in persistent mode, then you are just +doing it for a hobby and not professionally :-). ### g) libfuzzer fuzzer harnesses with LLVMFuzzerTestOneInput() -libfuzzer `LLVMFuzzerTestOneInput()` harnesses are the defacto standard -for fuzzing, and they can be used with AFL++ (and honggfuzz) as well! +libfuzzer `LLVMFuzzerTestOneInput()` harnesses are the defacto standard for +fuzzing, and they can be used with AFL++ (and honggfuzz) as well! Compiling them is as simple as: @@ -354,12 +356,15 @@ You can find many good examples of starting files in the Use the AFL++ tool `afl-cmin` to remove inputs from the corpus that do not produce a new path in the target. -Put all files from step a) into one directory, e.g. INPUTS. +Put all files from step a) into one directory, e.g., INPUTS. If the target program is to be called by fuzzing as `bin/target -d INPUTFILE` the run afl-cmin like this: + `afl-cmin -i INPUTS -o INPUTS_UNIQUE -- bin/target -d @@` -Note that the INPUTFILE argument that the target program would read from has to be set as `@@`. + +Note that the INPUTFILE argument that the target program would read from has to +be set as `@@`. If the target reads from stdin instead, just omit the `@@` as this is the default. @@ -369,8 +374,8 @@ This step is highly recommended! ### c) Minimizing all corpus files The shorter the input files that still traverse the same path within the target, -the better the fuzzing will be. This minimization is done with `afl-tmin` -however it is a long process as this has to be done for every file: +the better the fuzzing will be. This minimization is done with `afl-tmin`, +however, it is a long process as this has to be done for every file: ``` mkdir input @@ -380,8 +385,8 @@ for i in *; do done ``` -This step can also be parallelized, e.g. with `parallel`. Note that this step is -rather optional though. +This step can also be parallelized, e.g., with `parallel`. Note that this step +is rather optional though. ### Done! @@ -391,7 +396,7 @@ to be used in fuzzing! :-) ## 3. Fuzzing the target -In this final step we fuzz the target. There are not that many important options +In this final step, fuzz the target. There are not that many important options to run the target - unless you want to use many CPU cores/threads for the fuzzing, which will make the fuzzing much more useful. @@ -413,35 +418,38 @@ Note that both scripts improve your fuzzing performance but also decrease your system protection against attacks! So set strong firewall rules and only expose SSH as a network service if you use these (which is highly recommended). -If you have an input corpus from step 2 then specify this directory with the -`-i` option. Otherwise create a new directory and create a file with any content -as test data in there. +If you have an input corpus from step 2, then specify this directory with the +`-i` option. Otherwise, create a new directory and create a file with any +content as test data in there. If you do not want anything special, the defaults are already usually best, hence all you need is to specify the seed input directory with the result of step [2a) Collect inputs](#a-collect-inputs): + `afl-fuzz -i input -o output -- bin/target -d @@` -Note that the directory specified with -o will be created if it does not exist. + +Note that the directory specified with `-o` will be created if it does not +exist. It can be valuable to run afl-fuzz in a screen or tmux shell so you can log off, or afl-fuzz is not aborted if you are running it in a remote ssh session where -the connection fails in between. -Only do that though once you have verified that your fuzzing setup works! -Simply run it like `screen -dmS afl-main -- afl-fuzz -M main-$HOSTNAME -i ...` -and it will start away in a screen session. To enter this session simply type -`screen -r afl-main`. You see - it makes sense to name the screen session -same as the afl-fuzz -M/-S naming :-) -For more information on screen or tmux please check their documentation. +the connection fails in between. Only do that though once you have verified that +your fuzzing setup works! Run it like `screen -dmS afl-main -- afl-fuzz -M +main-$HOSTNAME -i ...` and it will start away in a screen session. To enter this +session, type `screen -r afl-main`. You see - it makes sense to name the screen +session same as the afl-fuzz -M/-S naming :-) For more information on screen or +tmux, check their documentation. If you need to stop and re-start the fuzzing, use the same command line options (or even change them by selecting a different power schedule or another mutation mode!) and switch the input directory with a dash (`-`): + `afl-fuzz -i - -o output -- bin/target -d @@` Adding a dictionary is helpful. See the directory [dictionaries/](../dictionaries/) if something is already included for your data format, and tell afl-fuzz to load that dictionary by adding `-x -dictionaries/FORMAT.dict`. With afl-clang-lto you have an autodictionary +dictionaries/FORMAT.dict`. With afl-clang-lto, you have an autodictionary generation for which you need to do nothing except to use afl-clang-lto as the compiler. You also have the option to generate a dictionary yourself, see [utils/libtokencap/README.md](../utils/libtokencap/README.md). @@ -457,15 +465,17 @@ handling in the target. Play around with various -m values until you find one that safely works for all your input seeds (if you have good ones and then double or quadruple that. -By default afl-fuzz never stops fuzzing. To terminate AFL++ simply press -Control-C or send a signal SIGINT. You can limit the number of executions or -approximate runtime in seconds with options also. +By default, afl-fuzz never stops fuzzing. To terminate AFL++, press Control-C or +send a signal SIGINT. You can limit the number of executions or approximate +runtime in seconds with options also. When you start afl-fuzz you will see a user interface that shows what the status is: +  -All labels are explained in [status_screen.md](status_screen.md). +All labels are explained in +[afl-fuzz_approach.md#understanding-the-status-screen](afl-fuzz_approach.md#understanding-the-status-screen). ### b) Keeping memory use and timeouts in check @@ -488,8 +498,8 @@ and not waste CPU time. ### c) Using multiple cores -If you want to seriously fuzz then use as many cores/threads as possible to fuzz -your target. +If you want to seriously fuzz, then use as many cores/threads as possible to +fuzz your target. On the same machine - due to the design of how AFL++ works - there is a maximum number of CPU cores/threads that are useful, use more and the overall @@ -503,7 +513,7 @@ can set the cache size (in MB) by setting the environment variable `AFL_TESTCACHE_SIZE`. There should be one main fuzzer (`-M main-$HOSTNAME` option) and as many -secondary fuzzers (e.g. `-S variant1`) as you have cores that you use. Every +secondary fuzzers (e.g., `-S variant1`) as you have cores that you use. Every -M/-S entry needs a unique name (that can be whatever), however, the same -o output directory location has to be used for all instances. @@ -522,14 +532,14 @@ All other secondaries should be used like this: * a quarter to a third with the MOpt mutator enabled: `-L 0` * run with a different power schedule, recommended are: `fast (default), explore, coe, lin, quad, exploit and rare` which you can set - with e.g. `-p explore` + with, e.g., `-p explore` * a few instances should use the old queue cycling with `-Z` Also, it is recommended to set `export AFL_IMPORT_FIRST=1` to load test cases from other fuzzers in the campaign first. -If you have a large corpus, a corpus from a previous run or are fuzzing in -a CI, then also set `export AFL_CMPLOG_ONLY_NEW=1` and `export AFL_FAST_CAL=1`. +If you have a large corpus, a corpus from a previous run or are fuzzing in a CI, +then also set `export AFL_CMPLOG_ONLY_NEW=1` and `export AFL_FAST_CAL=1`. You can also use different fuzzers. If you are using AFL spinoffs or AFL conforming fuzzers, then just use the same -o directory and give it a unique @@ -547,17 +557,16 @@ A long list can be found at However, you can also sync AFL++ with honggfuzz, libfuzzer with `-entropic=1`, etc. Just show the main fuzzer (-M) with the `-F` option where the queue/work -directory of a different fuzzer is, e.g. `-F /src/target/honggfuzz`. Using +directory of a different fuzzer is, e.g., `-F /src/target/honggfuzz`. Using honggfuzz (with `-n 1` or `-n 2`) and libfuzzer in parallel is highly recommended! ### d) Using multiple machines for fuzzing -Maybe you have more than one machine you want to fuzz the same target on. -Simply start the `afl-fuzz` (and perhaps libfuzzer, honggfuzz, ...) -orchestra as you like, just ensure that your have one and only one `-M` -instance per server, and that its name is unique, hence the recommendation -for `-M main-$HOSTNAME`. +Maybe you have more than one machine you want to fuzz the same target on. Start +the `afl-fuzz` (and perhaps libfuzzer, honggfuzz, ...) orchestra as you like, +just ensure that your have one and only one `-M` instance per server, and that +its name is unique, hence the recommendation for `-M main-$HOSTNAME`. Now there are three strategies on how you can sync between the servers: * never: sounds weird, but this makes every server an island and has the chance @@ -609,14 +618,14 @@ e.g., `afl-plot out/default /srv/www/htdocs/plot`. ### f) Stopping fuzzing, restarting fuzzing, adding new seeds -To stop an afl-fuzz run, simply press Control-C. +To stop an afl-fuzz run, press Control-C. To restart an afl-fuzz run, just reuse the same command line but replace the `-i directory` with `-i -` or set `AFL_AUTORESUME=1`. If you want to add new seeds to a fuzzing campaign you can run a temporary -fuzzing instance, e.g. when your main fuzzer is using `-o out` and the new seeds -are in `newseeds/` directory: +fuzzing instance, e.g., when your main fuzzer is using `-o out` and the new +seeds are in `newseeds/` directory: ``` AFL_BENCH_JUST_ONE=1 AFL_FAST_CAL=1 afl-fuzz -i newseeds -o out -S newseeds -- ./target @@ -649,7 +658,7 @@ An "easy" helper script for this is [https://github.com/vanhauser-thc/afl-cov](https://github.com/vanhauser-thc/afl-cov), just follow the README of that separate project. -If you see that an important area or a feature has not been covered so far then +If you see that an important area or a feature has not been covered so far, then try to find an input that is able to reach that and start a new secondary in that fuzzing campaign with that seed as input, let it run for a few minutes, then terminate it. The main node will pick it up and make it available to the @@ -659,15 +668,15 @@ AFL_TRY_AFFINITY=1` if you have no free core. Note that in nearly all cases you can never reach full coverage. A lot of functionality is usually dependent on exclusive options that would need individual fuzzing campaigns each with one of these options set. E.g., if you -fuzz a library to convert image formats and your target is the png to tiff API +fuzz a library to convert image formats and your target is the png to tiff API, then you will not touch any of the other library APIs and features. ### h) How long to fuzz a target? -This is a difficult question. Basically if no new path is found for a long time -(e.g. for a day or a week) then you can expect that your fuzzing won't be +This is a difficult question. Basically, if no new path is found for a long time +(e.g., for a day or a week), then you can expect that your fuzzing won't be fruitful anymore. However, often this just means that you should switch out -secondaries for others, e.g. custom mutator modules, sync to very different +secondaries for others, e.g., custom mutator modules, sync to very different fuzzers, etc. Keep the queue/ directory (for future fuzzings of the same or similar targets) @@ -722,7 +731,7 @@ just for AFL++). Here are some of the most important caveats for AFL++: - AFL++ detects faults by checking for the first spawned process dying due to a - signal (SIGSEGV, SIGABRT, etc). Programs that install custom handlers for + signal (SIGSEGV, SIGABRT, etc.). Programs that install custom handlers for these signals may need to have the relevant code commented out. In the same vein, faults in child processes spawned by the fuzzed target may evade detection unless you manually add some code to catch that. @@ -800,7 +809,6 @@ then color-codes the input based on which sections appear to be critical, and which are not; while not bulletproof, it can often offer quick insights into complex file formats. - ## 5. CI fuzzing Some notes on CI fuzzing - this fuzzing is different to normal fuzzing campaigns diff --git a/docs/ideas.md b/docs/ideas.md index 325e7031..52b07c26 100644 --- a/docs/ideas.md +++ b/docs/ideas.md @@ -1,58 +1,57 @@ # Ideas for AFL++ -In the following, we describe a variety of ideas that could be implemented -for future AFL++ versions. +In the following, we describe a variety of ideas that could be implemented for +future AFL++ versions. ## Analysis software -Currently analysis is done by using afl-plot, which is rather outdated. -A GTK or browser tool to create run-time analysis based on fuzzer_stats, -queue/id* information and plot_data that allows for zooming in and out, -changing min/max display values etc. and doing that for a single run, -different runs and campaigns vs campaigns. -Interesting values are execs, and execs/s, edges discovered (total, when -each edge was discovered and which other fuzzer share finding that edge), -test cases executed. -It should be clickable which value is X and Y axis, zoom factor, log scaling -on-off, etc. +Currently analysis is done by using afl-plot, which is rather outdated. A GTK or +browser tool to create run-time analysis based on fuzzer_stats, queue/id* +information and plot_data that allows for zooming in and out, changing min/max +display values etc. and doing that for a single run, different runs and +campaigns vs. campaigns. Interesting values are execs, and execs/s, edges +discovered (total, when each edge was discovered and which other fuzzer share +finding that edge), test cases executed. It should be clickable which value is X +and Y axis, zoom factor, log scaling on-off, etc. Mentor: vanhauser-thc ## WASM Instrumentation Currently, AFL++ can be used for source code fuzzing and traditional binaries. -With the rise of WASM as compile target, however, a novel way of -instrumentation needs to be implemented for binaries compiled to Webassembly. -This can either be done by inserting instrumentation directly into the -WASM AST, or by patching feedback into a WASM VMs of choice, similar to -the current Unicorn instrumentation. +With the rise of WASM as compile target, however, a novel way of instrumentation +needs to be implemented for binaries compiled to Webassembly. This can either be +done by inserting instrumentation directly into the WASM AST, or by patching +feedback into a WASM VMs of choice, similar to the current Unicorn +instrumentation. Mentor: any ## Support other programming languages Other programming languages also use llvm hence they could (easily?) supported -for fuzzing, e.g. mono, swift, go, kotlin native, fortran, ... +for fuzzing, e.g., mono, swift, go, kotlin native, fortran, ... -GCC also supports: Objective-C, Fortran, Ada, Go, and D -(according to [Gcc homepage](https://gcc.gnu.org/)) +GCC also supports: Objective-C, Fortran, Ada, Go, and D (according to +[Gcc homepage](https://gcc.gnu.org/)) -LLVM is also used by: Rust, LLGo (Go), kaleidoscope (Haskell), flang (Fortran), emscripten (JavaScript, WASM), ilwasm (CIL (C#)) -(according to [LLVM frontends](https://gist.github.com/axic/62d66fb9d8bccca6cc48fa9841db9241)) +LLVM is also used by: Rust, LLGo (Go), kaleidoscope (Haskell), flang (Fortran), +emscripten (JavaScript, WASM), ilwasm (CIL (C#)) (according to +[LLVM frontends](https://gist.github.com/axic/62d66fb9d8bccca6cc48fa9841db9241)) Mentor: vanhauser-thc ## Machine Learning -Something with machine learning, better than [NEUZZ](https://github.com/dongdongshe/neuzz) :-) -Either improve a single mutator thorugh learning of many different bugs -(a bug class) or gather deep insights about a single target beforehand -(CFG, DFG, VFG, ...?) and improve performance for a single target. +Something with machine learning, better than +[NEUZZ](https://github.com/dongdongshe/neuzz) :-) Either improve a single +mutator through learning of many different bugs (a bug class) or gather deep +insights about a single target beforehand (CFG, DFG, VFG, ...?) and improve +performance for a single target. Mentor: domenukk ## Your idea! -Finally, we are open to proposals! -Create an issue at https://github.com/AFLplusplus/AFLplusplus/issues and let's discuss :-) - +Finally, we are open to proposals! Create an issue at +https://github.com/AFLplusplus/AFLplusplus/issues and let's discuss :-)
\ No newline at end of file diff --git a/docs/important_changes.md b/docs/important_changes.md index 877dfab2..d5e67f75 100644 --- a/docs/important_changes.md +++ b/docs/important_changes.md @@ -1,55 +1,57 @@ # Important changes in AFL++ -This document lists important changes in AFL++, for example, major behaviour changes. +This document lists important changes in AFL++, for example, major behavior +changes. ## From version 3.00 onwards -With AFL++ 3.13-3.20 we introduce frida_mode (-O) to have an alternative for -binary-only fuzzing. It is slower than Qemu mode but works on MacOS, Android, +With AFL++ 3.13-3.20, we introduce FRIDA mode (`-O`) to have an alternative for +binary-only fuzzing. It is slower than QEMU mode but works on MacOS, Android, iOS etc. -With AFL++ 3.15 we introduced the following changes from previous behaviours: +With AFL++ 3.15, we introduced the following changes from previous behaviors: * Also -M main mode does not do deterministic fuzzing by default anymore - * afl-cmin and afl-showmap -Ci now descent into subdirectories like - afl-fuzz -i does (but note that afl-cmin.bash does not) + * afl-cmin and afl-showmap -Ci now descent into subdirectories like afl-fuzz + -i does (but note that afl-cmin.bash does not) -With AFL++ 3.14 we introduced the following changes from previous behaviours: +With AFL++ 3.14, we introduced the following changes from previous behaviors: * afl-fuzz: deterministic fuzzing it not a default for -M main anymore - * afl-cmin/afl-showmap -i now descends into subdirectories (afl-cmin.bash - however does not) + * afl-cmin/afl-showmap -i now descends into subdirectories (afl-cmin.bash, + however, does not) -With AFL++ 3.10 we introduced the following changes from previous behaviours: +With AFL++ 3.10, we introduced the following changes from previous behaviors: * The '+' feature of the '-t' option now means to auto-calculate the timeout with the value given being the maximum timeout. The original meaning of "skipping timeouts instead of abort" is now inherent to the -t option. -With AFL++ 3.00 we introduced changes that break some previous AFL and AFL++ -behaviours and defaults: +With AFL++ 3.00, we introduced changes that break some previous AFL and AFL++ +behaviors and defaults: * There are no llvm_mode and gcc_plugin subdirectories anymore and there is only one compiler: afl-cc. All previous compilers now symlink to this one. All instrumentation source code is now in the `instrumentation/` folder. * The gcc_plugin was replaced with a new version submitted by AdaCore that supports more features. Thank you! - * qemu_mode got upgraded to QEMU 5.1, but to be able to build this a current - ninja build tool version and python3 setuptools are required. - qemu_mode also got new options like snapshotting, instrumenting specific - shared libraries, etc. Additionally QEMU 5.1 supports more CPU targets so - this is really worth it. + * QEMU mode got upgraded to QEMU 5.1, but to be able to build this a current + ninja build tool version and python3 setuptools are required. QEMU mode also + got new options like snapshotting, instrumenting specific shared libraries, + etc. Additionally QEMU 5.1 supports more CPU targets so this is really worth + it. * When instrumenting targets, afl-cc will not supersede optimizations anymore if any were given. This allows to fuzz targets build regularly like those for debug or release versions. * afl-fuzz: - * if neither -M or -S is specified, `-S default` is assumed, so more - fuzzers can easily be added later - * `-i` input directory option now descends into subdirectories. It also - does not fatal on crashes and too large files, instead it skips them - and uses them for splicing mutations - * -m none is now default, set memory limits (in MB) with e.g. -m 250 - * deterministic fuzzing is now disabled by default (unless using -M) and - can be enabled with -D + * if neither -M or -S is specified, `-S default` is assumed, so more fuzzers + can easily be added later + * `-i` input directory option now descends into subdirectories. It also does + not fatal on crashes and too large files, instead it skips them and uses + them for splicing mutations + * -m none is now default, set memory limits (in MB) with, e.g., -m 250 + * deterministic fuzzing is now disabled by default (unless using -M) and can + be enabled with -D * a caching of test cases can now be performed and can be modified by - editing config.h for TESTCASE_CACHE or by specifying the env variable - `AFL_TESTCACHE_SIZE` (in MB). Good values are between 50-500 (default: 50). + editing config.h for TESTCASE_CACHE or by specifying the environment + variable `AFL_TESTCACHE_SIZE` (in MB). Good values are between 50-500 + (default: 50). * -M mains do not perform trimming * examples/ got renamed to utils/ * libtokencap/ libdislocator/ and qdbi_mode/ were moved to utils/ diff --git a/docs/rpc_statsd.md b/docs/rpc_statsd.md index 9b3d8d40..003b9c79 100644 --- a/docs/rpc_statsd.md +++ b/docs/rpc_statsd.md @@ -1,18 +1,29 @@ # Remote monitoring and metrics visualization -AFL++ can send out metrics as StatsD messages. For remote monitoring and visualization of the metrics, you can set up a tool chain. For example, with Prometheus and Grafana. All tools are free and open source. +AFL++ can send out metrics as StatsD messages. For remote monitoring and +visualization of the metrics, you can set up a tool chain. For example, with +Prometheus and Grafana. All tools are free and open source. -This enables you to create nice and readable dashboards containing all the information you need on your fuzzer instances. There is no need to write your own statistics parsing system, deploy and maintain it to all your instances, and sync with your graph rendering system. +This enables you to create nice and readable dashboards containing all the +information you need on your fuzzer instances. There is no need to write your +own statistics parsing system, deploy and maintain it to all your instances, and +sync with your graph rendering system. -Compared to the default integrated UI of AFL++, this can help you to visualize trends and the fuzzing state over time. You might be able to see when the fuzzing process has reached a state of no progress and visualize what are the "best strategies" for your targets (according to your own criteria). You can do so without logging into each instance individually. +Compared to the default integrated UI of AFL++, this can help you to visualize +trends and the fuzzing state over time. You might be able to see when the +fuzzing process has reached a state of no progress and visualize what are the +"best strategies" for your targets (according to your own criteria). You can do +so without logging into each instance individually.  -This is an example visualization with Grafana. The dashboard can be imported with [this JSON template](resources/grafana-afl++.json). +This is an example visualization with Grafana. The dashboard can be imported +with [this JSON template](resources/grafana-afl++.json). ## AFL++ metrics and StatsD -StatsD allows you to receive and aggregate metrics from a wide range of applications and retransmit them to a backend of your choice. +StatsD allows you to receive and aggregate metrics from a wide range of +applications and retransmit them to a backend of your choice. From AFL++, StatsD can receive the following metrics: - cur_path @@ -36,35 +47,57 @@ From AFL++, StatsD can receive the following metrics: - var_byte_count - variable_paths -Depending on your StatsD server, you will be able to monitor, trigger alerts, or perform actions based on these metrics (for example: alert on slow exec/s for a new build, threshold of crashes, time since last crash > X, and so on). +Depending on your StatsD server, you will be able to monitor, trigger alerts, or +perform actions based on these metrics (for example: alert on slow exec/s for a +new build, threshold of crashes, time since last crash > X, and so on). ## Setting environment variables in AFL++ -1. To enable the StatsD metrics collection on your fuzzer instances, set the environment variable `AFL_STATSD=1`. By default, AFL++ will send the metrics over UDP to 127.0.0.1:8125. +1. To enable the StatsD metrics collection on your fuzzer instances, set the + environment variable `AFL_STATSD=1`. By default, AFL++ will send the metrics + over UDP to 127.0.0.1:8125. -2. To enable tags for each metric based on their format (banner and afl_version), set the environment variable `AFL_STATSD_TAGS_FLAVOR`. By default, no tags will be added to the metrics. +2. To enable tags for each metric based on their format (banner and + afl_version), set the environment variable `AFL_STATSD_TAGS_FLAVOR`. By + default, no tags will be added to the metrics. The available values are the following: - `dogstatsd` - `influxdb` - `librato` - `signalfx` - - For more information on environment variables, see [env_variables.md](env_variables.md). - Note: When using multiple fuzzer instances with StatsD it is *strongly* recommended to set up `AFL_STATSD_TAGS_FLAVOR` to match your StatsD server. This will allow you to see individual fuzzer performance, detect bad ones, and see the progress of each strategy. + For more information on environment variables, see + [env_variables.md](env_variables.md). -3. Optional: To set the host and port of your StatsD daemon, set `AFL_STATSD_HOST` and `AFL_STATSD_PORT`. The default values are `localhost` and `8125`. + Note: When using multiple fuzzer instances with StatsD it is *strongly* + recommended to set up `AFL_STATSD_TAGS_FLAVOR` to match your StatsD server. + This will allow you to see individual fuzzer performance, detect bad ones, + and see the progress of each strategy. + +3. Optional: To set the host and port of your StatsD daemon, set + `AFL_STATSD_HOST` and `AFL_STATSD_PORT`. The default values are `localhost` + and `8125`. ## Installing and setting up StatsD, Prometheus, and Grafana -The easiest way to install and set up the infrastructure is with Docker and Docker Compose. +The easiest way to install and set up the infrastructure is with Docker and +Docker Compose. -Depending on your fuzzing setup and infrastructure, you may not want to run these applications on your fuzzer instances. This setup may be modified before use in a production environment; for example, adding passwords, creating volumes for storage, tweaking the metrics gathering to get host metrics (CPU, RAM, and so on). +Depending on your fuzzing setup and infrastructure, you may not want to run +these applications on your fuzzer instances. This setup may be modified before +use in a production environment; for example, adding passwords, creating volumes +for storage, tweaking the metrics gathering to get host metrics (CPU, RAM, and +so on). -For all your fuzzing instances, only one instance of Prometheus and Grafana is required. The [statsd exporter](https://registry.hub.docker.com/r/prom/statsd-exporter) converts the StatsD metrics to Prometheus. If you are using a provider that supports StatsD directly, you can skip this part of the setup." +For all your fuzzing instances, only one instance of Prometheus and Grafana is +required. The +[statsd exporter](https://registry.hub.docker.com/r/prom/statsd-exporter) +converts the StatsD metrics to Prometheus. If you are using a provider that +supports StatsD directly, you can skip this part of the setup." -You can create and move the infrastructure files into a directory of your choice. The directory will store all the required configuration files. +You can create and move the infrastructure files into a directory of your +choice. The directory will store all the required configuration files. To install and set up Prometheus and Grafana: @@ -76,6 +109,7 @@ To install and set up Prometheus and Grafana: ``` 2. Create a `docker-compose.yml` containing the following: + ```yml version: '3' @@ -109,7 +143,7 @@ To install and set up Prometheus and Grafana: - "8125:9125/udp" networks: - statsd-net - + grafana: image: grafana/grafana container_name: grafana @@ -134,7 +168,8 @@ To install and set up Prometheus and Grafana: ``` 4. Create a `statsd_mapping.yml` containing the following: - ```yml + + ```yml mappings: - match: "fuzzing.*" name: "fuzzing" @@ -152,4 +187,4 @@ To run your fuzzing instances: AFL_STATSD_TAGS_FLAVOR=dogstatsd AFL_STATSD=1 afl-fuzz -M test-fuzzer-1 -i i -o o [./bin/my-application] @@ AFL_STATSD_TAGS_FLAVOR=dogstatsd AFL_STATSD=1 afl-fuzz -S test-fuzzer-2 -i i -o o [./bin/my-application] @@ ... -``` +```
\ No newline at end of file diff --git a/frida_mode/DEBUGGING.md b/frida_mode/DEBUGGING.md index 9cdc5eb6..207a48bf 100644 --- a/frida_mode/DEBUGGING.md +++ b/frida_mode/DEBUGGING.md @@ -95,7 +95,7 @@ gdb \ ``` Note: -- We have to manually set the `__AFL_PERSISTENT` environment variable which is +- You have to manually set the `__AFL_PERSISTENT` environment variable which is usually passed by `afl-fuzz`. - Setting breakpoints etc. is likely to interfere with FRIDA and cause spurious errors. @@ -160,9 +160,9 @@ Lastly, if your defect only occurs when using `afl-fuzz` (e.g., when using shared memory mapping being created for it to record its data), it is possible to enable the creation of a core dump for post-mortem analysis. -Firstly, check if your `/proc/sys/kernel/core_pattern` configuration is simply -set to a filename (AFL++ encourages you to set it to the value `core` in any -case since it doesn't want any handler applications getting in the way). +Firstly, check if your `/proc/sys/kernel/core_pattern` configuration is set to a +filename (AFL++ encourages you to set it to the value `core` in any case since +it doesn't want any handler applications getting in the way). Next, set `ulimit -c unlimited` to remove any size limitations for core files. diff --git a/frida_mode/MapDensity.md b/frida_mode/MapDensity.md index b6a96ca0..50f2720f 100644 --- a/frida_mode/MapDensity.md +++ b/frida_mode/MapDensity.md @@ -77,13 +77,13 @@ evenly distributed. We start with a large address and need to discard a large number of the bits to generate a block ID which is within range. But how do we choose the unique bits of the address versus those which are the same for every block? The high bits of -the address may simply be all `0s` or all `1s` to make the address canonical, -the middle portion of the address may be the same for all blocks (since if they -are all within the same binary, then they will all be adjacent in memory), and -on some systems, even the low bits may have poor entropy as some use fixed -length aligned instructions. Then we need to consider that a portion of each -binary may contain the `.data` or `.bss` sections and so may not contain any -blocks of code at all. +the address may be all `0s` or all `1s` to make the address canonical, the +middle portion of the address may be the same for all blocks (since if they are +all within the same binary, then they will all be adjacent in memory), and on +some systems, even the low bits may have poor entropy as some use fixed length +aligned instructions. Then we need to consider that a portion of each binary may +contain the `.data` or `.bss` sections and so may not contain any blocks of code +at all. ### Edge IDs diff --git a/frida_mode/README.md b/frida_mode/README.md index c19280e1..08f6b891 100644 --- a/frida_mode/README.md +++ b/frida_mode/README.md @@ -120,9 +120,9 @@ x86 and x64 architectures. Implementation details can be found Dynamic instrumentation is used to augment the target application with similar coverage information to that inserted by `afl-gcc` or `afl-clang`. The shared -library is also linked to the `compiler-rt` component of AFLplusplus to feedback -this coverage information to AFL++ and also provide a fork server. It also makes -use of the FRIDA +library is also linked to the `compiler-rt` component of AFL++ to feedback this +coverage information to AFL++ and also provide a fork server. It also makes use +of the FRIDA [prefetch](https://github.com/frida/frida-gum/blob/56dd9ba3ee9a5511b4b0c629394bf122775f1ab7/gum/gumstalker.h#L115) support to feedback instrumented blocks from the child to the parent using a shared memory region to avoid the need to regenerate instrumented blocks on each @@ -141,6 +141,7 @@ instances run CMPLOG mode and instrumentation of the binary is less frequent (only on CMP, SUB and CALL instructions) performance is not quite so critical. ## Advanced configuration options + * `AFL_FRIDA_DRIVER_NO_HOOK` - See `AFL_QEMU_DRIVER_NO_HOOK`. When using the QEMU driver to provide a `main` loop for a user provided `LLVMFuzzerTestOneInput`, this option configures the driver to read input from @@ -229,9 +230,9 @@ instances run CMPLOG mode and instrumentation of the binary is less frequent * `AFL_FRIDA_STATS_FILE` - Write statistics information about the code being instrumented to the given file name. The statistics are written only for the child process when new block is instrumented (when the - `AFL_FRIDA_STATS_INTERVAL` has expired). Note that simply because a new path - is found does not mean a new block needs to be compiled. It could simply be - that the existing blocks instrumented have been executed in a different order. + `AFL_FRIDA_STATS_INTERVAL` has expired). Note that just because a new path is + found does not mean a new block needs to be compiled. It could be that the + existing blocks instrumented have been executed in a different order. ``` stats @@ -359,16 +360,16 @@ An example of how to fuzz a dynamic library on OSX is included, see [test/osx-lib](test/osx-lib). This requires the use of a simple test harness executable which will load the library and call a target function within it. The dependent library can either be loaded in using `dlopen` and `dlsym` in a -function marked `__attribute__((constructor()))` or the test harness can simply -be linked against it. It is important that the target library is loaded before +function marked `__attribute__((constructor()))` or the test harness can be +linked against it. It is important that the target library is loaded before execution of `main`, since this is the point where FRIDA mode is initialized. Otherwise, it will not be possible to configure coverage for the test library using `AFL_FRIDA_INST_RANGES` or similar. ## Debugging -Please refer to [DEBUGGING.md](DEBUGGING.md) for assistance should you encounter -problems with FRIDA mode. +Should you encounter problems with FRIDA mode, refer to +[DEBUGGING.md](DEBUGGING.md) for assistance. ## To do diff --git a/frida_mode/Scripting.md b/frida_mode/Scripting.md index fcf8a490..ad86fdd3 100644 --- a/frida_mode/Scripting.md +++ b/frida_mode/Scripting.md @@ -109,8 +109,8 @@ Afl.setPersistentAddress(address); A persistent hook can be implemented using a conventional shared object, sample source code for a hook suitable for the prototype of `LLVMFuzzerTestOneInput` -can be found in [hook/hook.c](hook/hook.c). This can be configured using code -similar to the following. +can be found in [hook/](hook/). This can be configured using code similar to the +following. ```js const path = Afl.module.path; @@ -334,8 +334,8 @@ Interceptor.replace(LLVMFuzzerTestOneInput, cm.My_LLVMFuzzerTestOneInput); ### Hooking `main` -Lastly, it should be noted that using FRIDA mode's scripting support to hook -the `main` function is a special case. This is because the `main` function is +Lastly, it should be noted that using FRIDA mode's scripting support to hook the +`main` function is a special case. This is because the `main` function is already hooked by the FRIDA mode engine itself and hence the function `main` (or at least the first basic block already been compiled by Stalker ready for execution). Hence any attempt to use `Interceptor.replace` like in the example @@ -405,22 +405,22 @@ Consider the [following](test/js/test2.c) test code... #include <unistd.h> const uint32_t crc32_tab[] = { - 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, + 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, ... - 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d + 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d }; uint32_t crc32(const void *buf, size_t size) { - const uint8_t *p = buf; - uint32_t crc; - crc = ~0U; - while (size--) - crc = crc32_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8); - return crc ^ ~0U; + const uint8_t *p = buf; + uint32_t crc; + crc = ~0U; + while (size--) + crc = crc32_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8); + return crc ^ ~0U; } /* @@ -511,7 +511,7 @@ int main(int argc, char **argv) { ``` There are a couple of obstacles with our target application. Unlike when fuzzing -source code, though, we can't simply edit it and recompile it. The following +source code, though, we can't just edit it and recompile it. The following script shows how we can use the normal functionality of FRIDA to modify any troublesome behavior. diff --git a/instrumentation/README.gcc_plugin.md b/instrumentation/README.gcc_plugin.md index f251415b..ef38662b 100644 --- a/instrumentation/README.gcc_plugin.md +++ b/instrumentation/README.gcc_plugin.md @@ -1,7 +1,7 @@ # GCC-based instrumentation for afl-fuzz -For the general instruction manual, see [../README.md](../README.md). -For the LLVM-based instrumentation, see [README.llvm.md](README.llvm.md). +For the general instruction manual, see [../README.md](../README.md). For the +LLVM-based instrumentation, see [README.llvm.md](README.llvm.md). This document describes how to build and use `afl-gcc-fast` and `afl-g++-fast`, which instrument the target with the help of gcc plugins. diff --git a/instrumentation/README.instrument_list.md b/instrumentation/README.instrument_list.md index b412b600..3ed64807 100644 --- a/instrumentation/README.instrument_list.md +++ b/instrumentation/README.instrument_list.md @@ -128,4 +128,4 @@ Note that whitespace is ignored and comments (`# foo`) are supported. ### 3b) UNIX-style pattern matching You can add UNIX-style pattern matching in the "instrument file list" entries. -See `man fnmatch` for the syntax. We do not set any of the `fnmatch` flags.
\ No newline at end of file +See `man fnmatch` for the syntax. Do not set any of the `fnmatch` flags.
\ No newline at end of file diff --git a/instrumentation/README.laf-intel.md b/instrumentation/README.laf-intel.md index 3cde10c3..06e653ea 100644 --- a/instrumentation/README.laf-intel.md +++ b/instrumentation/README.laf-intel.md @@ -42,9 +42,9 @@ comparisons. A new experimental feature is splitting floating point comparisons into a series of sign, exponent and mantissa comparisons followed by splitting each of them into 8 bit comparisons when necessary. It is activated with the -`AFL_LLVM_LAF_SPLIT_FLOATS` setting. Please note that full IEEE 754 -functionality is not preserved, that is values of nan and infinity will probably -behave differently. +`AFL_LLVM_LAF_SPLIT_FLOATS` setting. Note that full IEEE 754 functionality is +not preserved, that is values of nan and infinity will probably behave +differently. Note that setting this automatically activates `AFL_LLVM_LAF_SPLIT_COMPARES`. diff --git a/instrumentation/README.llvm.md b/instrumentation/README.llvm.md index 88ea0127..d220e52c 100644 --- a/instrumentation/README.llvm.md +++ b/instrumentation/README.llvm.md @@ -40,7 +40,7 @@ The idea and much of the initial implementation came from Laszlo Szekeres. ## 2a) How to use this - short -Set the `LLVM_CONFIG` variable to the clang version you want to use, e.g. +Set the `LLVM_CONFIG` variable to the clang version you want to use, e.g.: ``` LLVM_CONFIG=llvm-config-9 make @@ -106,9 +106,10 @@ either setting `AFL_CC_COMPILER=LLVM` or pass the parameter `--afl-llvm` via CFLAGS/CXXFLAGS/CPPFLAGS. The tool honors roughly the same environmental variables as afl-gcc (see -[docs/env_variables.md](../docs/env_variables.md)). This includes AFL_USE_ASAN, -AFL_HARDEN, and AFL_DONT_OPTIMIZE. However AFL_INST_RATIO is not honored as it -does not serve a good purpose with the more effective PCGUARD analysis. +[docs/env_variables.md](../docs/env_variables.md)). This includes +`AFL_USE_ASAN`, `AFL_HARDEN`, and `AFL_DONT_OPTIMIZE`. However, `AFL_INST_RATIO` +is not honored as it does not serve a good purpose with the more effective +PCGUARD analysis. ## 3) Options @@ -119,15 +120,15 @@ If you need just to instrument specific parts of the code, you can the instrument file list which C/C++ files to actually instrument. See [README.instrument_list.md](README.instrument_list.md) -For splitting memcmp, strncmp, etc. please see -[README.laf-intel.md](README.laf-intel.md) +For splitting memcmp, strncmp, etc., see +[README.laf-intel.md](README.laf-intel.md). Then there are different ways of instrumenting the target: -1. An better instrumentation strategy uses LTO and link time instrumentation. - Note that not all targets can compile in this mode, however if it works it is - the best option you can use. Simply use afl-clang-lto/afl-clang-lto++ to use - this option. See [README.lto.md](README.lto.md). +1. A better instrumentation strategy uses LTO and link time instrumentation. + Note that not all targets can compile in this mode, however, if it works it + is the best option you can use. To go with this option, use + afl-clang-lto/afl-clang-lto++. See [README.lto.md](README.lto.md). 2. Alternatively you can choose a completely different coverage method: @@ -157,8 +158,8 @@ nozero counter default for performance reasons. ## 4) deferred initialization, persistent mode, shared memory fuzzing -This is the most powerful and effective fuzzing you can do. Please see -[README.persistent_mode.md](README.persistent_mode.md) for a full explanation. +This is the most powerful and effective fuzzing you can do. For a full +explanation, see [README.persistent_mode.md](README.persistent_mode.md). ## 5) Bonus feature: 'dict2file' pass @@ -217,7 +218,7 @@ by Jinghan Wang, et. al. Note that the original implementation (available [here](https://github.com/bitsecurerlab/afl-sensitive)) is built on top of AFL's -qemu_mode. This is essentially a port that uses LLVM vectorized instructions +QEMU mode. This is essentially a port that uses LLVM vectorized instructions (available from llvm versions 4.0.1 and higher) to achieve the same results when compiling source code. @@ -233,4 +234,45 @@ are 2-16. It is highly recommended to increase the MAP_SIZE_POW2 definition in config.h to at least 18 and maybe up to 20 for this as otherwise too many map collisions -occur.
\ No newline at end of file +occur. + +## 8) NeverZero counters + +In larger, complex, or reiterative programs, the byte sized counters that +collect the edge coverage can easily fill up and wrap around. This is not that +much of an issue - unless, by chance, it wraps just to a value of zero when the +program execution ends. In this case, afl-fuzz is not able to see that the edge +has been accessed and will ignore it. + +NeverZero prevents this behavior. If a counter wraps, it jumps over the value 0 +directly to a 1. This improves path discovery (by a very small amount) at a very +low cost (one instruction per edge). + +(The alternative of saturated counters has been tested also and proved to be +inferior in terms of path discovery.) + +This is implemented in afl-gcc and afl-gcc-fast, however, for llvm_mode this is +optional if multithread safe counters are selected or the llvm version is below +9 - as there are severe performance costs in these cases. + +If you want to enable this for llvm versions below 9 or thread safe counters, +then set + +``` +export AFL_LLVM_NOT_ZERO=1 +``` + +In case you are on llvm 9 or greater and you do not want this behavior, then you +can set: + +``` +AFL_LLVM_SKIP_NEVERZERO=1 +``` + +If the target does not have extensive loops or functions that are called a lot, +then this can give a small performance boost. + +Please note that the default counter implementations are not thread safe! + +Support for thread safe counters in mode LLVM CLASSIC can be activated with +setting `AFL_LLVM_THREADSAFE_INST=1`.
\ No newline at end of file diff --git a/instrumentation/README.lto.md b/instrumentation/README.lto.md index a74425dc..a20175b1 100644 --- a/instrumentation/README.lto.md +++ b/instrumentation/README.lto.md @@ -71,7 +71,7 @@ use an outdated Linux distribution, read the next section. Installing the llvm snapshot builds is easy and mostly painless: In the following line, change `NAME` for your Debian or Ubuntu release name -(e.g. buster, focal, eon, etc.): +(e.g., buster, focal, eon, etc.): ``` echo deb http://apt.llvm.org/NAME/ llvm-toolchain-NAME NAME >> /etc/apt/sources.list @@ -202,7 +202,7 @@ bytes or which functions were touched by an input. ## Solving difficult targets Some targets are difficult because the configure script does unusual stuff that -is unexpected for afl. See the next chapter `Potential issues` for how to solve +is unexpected for afl. See the next section `Potential issues` for how to solve these. ### Example: ffmpeg @@ -328,7 +328,7 @@ and `CXXFLAGS=-flto=full`). If this succeeds, then there is an issue with afl-clang-lto. Please report at [https://github.com/AFLplusplus/AFLplusplus/issues/226](https://github.com/AFLplusplus/AFLplusplus/issues/226). -Even some targets where clang-12 fails can be build if the fail is just in +Even some targets where clang-12 fails can be built if the fail is just in `./configure`, see `Solving difficult targets` above. ## History diff --git a/qemu_mode/README.md b/qemu_mode/README.md index b4b5e7bf..8e04cbf9 100644 --- a/qemu_mode/README.md +++ b/qemu_mode/README.md @@ -83,8 +83,9 @@ For more information, see [README.persistent.md](README.persistent.md). As an extension to persistent mode, qemuafl can snapshot and restore the memory state and brk(). For details, see [README.persistent.md](README.persistent.md). -The env var that enables the ready to use snapshot mode is `AFL_QEMU_SNAPSHOT` -and takes a hex address as a value that is the snapshot entry point. +The environment variable that enables the ready to use snapshot mode is +`AFL_QEMU_SNAPSHOT` and takes a hex address as a value that is the snapshot +entry point. Snapshot mode can work restoring all the writeable pages, that is typically slower than fork() mode but, on the other hand, it can scale better with diff --git a/qemu_mode/README.persistent.md b/qemu_mode/README.persistent.md index 7210a8cc..ab45860d 100644 --- a/qemu_mode/README.persistent.md +++ b/qemu_mode/README.persistent.md @@ -17,10 +17,10 @@ The start of the persistent loop has to be set with environment variable `AFL_QEMU_PERSISTENT_ADDR`. This address can be the address of whatever instruction. Setting this address to -the start of a function makes the usage simple. If the address is however within -a function, either RET, OFFSET, or EXITS (see below in 2.2, 2.3, 2.6) have to be -set. This address (as well as the RET address, see below) has to be defined in -hexadecimal with the 0x prefix or as a decimal value. +the start of a function makes the usage simple. If the address is, however, +within a function, either RET, OFFSET, or EXITS (see below in 2.2, 2.3, 2.6) +have to be set. This address (as well as the RET address, see below) has to be +defined in hexadecimal with the 0x prefix or as a decimal value. If both RET and EXITS are not set, QEMU will assume that START points to a function and will patch the return address (on stack or in the link register) to diff --git a/qemu_mode/libcompcov/README.md b/qemu_mode/libcompcov/README.md index fca20a69..bb010d8f 100644 --- a/qemu_mode/libcompcov/README.md +++ b/qemu_mode/libcompcov/README.md @@ -18,12 +18,12 @@ and this module is not capable to log the coverage in this case. If you have the source code of the fuzzing target you should nto use this library and QEMU but build it with afl-clang-fast and the laf-intel options. -To use this library make sure to preload it with AFL_PRELOAD. +To use this library, make sure to preload it with AFL_PRELOAD. ``` export AFL_PRELOAD=/path/to/libcompcov.so export AFL_COMPCOV_LEVEL=1 - + afl-fuzz -Q -i input -o output <your options> -- <target args> ``` @@ -31,7 +31,7 @@ The AFL_COMPCOV_LEVEL tells to QEMU and libcompcov how to log comaprisons. Level 1 logs just comparison with immediates / read-only memory and level 2 logs all the comparisons. -The library make use of https://github.com/ouadev/proc_maps_parser and so it is -Linux specific. However this is not a strict dependency, other UNIX operating -systems can be supported simply replacing the code related to the -/proc/self/maps parsing. +The library makes use of https://github.com/ouadev/proc_maps_parser and so it is +Linux specific. However, this is not a strict dependency, other UNIX operating +systems can be supported by replacing the code related to the /proc/self/maps +parsing.
\ No newline at end of file diff --git a/qemu_mode/libqasan/README.md b/qemu_mode/libqasan/README.md index 6a65c12b..41195933 100644 --- a/qemu_mode/libqasan/README.md +++ b/qemu_mode/libqasan/README.md @@ -9,7 +9,7 @@ and this runtime is injected via LD_PRELOAD (so works just for dynamically linked binaries). The usage is super simple, just set the env var `AFL_USE_QASAN=1` when fuzzing -in qemu mode (-Q). afl-fuzz will automatically set AFL_PRELOAD to load this +in QEMU mode (-Q). afl-fuzz will automatically set AFL_PRELOAD to load this library and enable the QASan instrumentation in afl-qemu-trace. For debugging purposes, we still suggest to run the original QASan as the diff --git a/testcases/README.md b/testcases/README.md index ef38d3c4..a2f74d68 100644 --- a/testcases/README.md +++ b/testcases/README.md @@ -1,4 +1,4 @@ -# AFL starting test cases +# AFL++ starting test cases (See [../README.md](../README.md) for the general instruction manual.) diff --git a/unicorn_mode/README.md b/unicorn_mode/README.md index d2b7d16f..ee4a7b22 100644 --- a/unicorn_mode/README.md +++ b/unicorn_mode/README.md @@ -8,10 +8,11 @@ The CompareCoverage and NeverZero counters features are by Andrea Fioraldi <andr ## 1) Introduction -The code in ./unicorn_mode allows you to build the (Unicorn Engine)[https://github.com/unicorn-engine/unicorn] with AFL support. +The code in ./unicorn_mode allows you to build the +(Unicorn Engine)[https://github.com/unicorn-engine/unicorn] with AFL++ support. This means, you can run anything that can be emulated in unicorn and obtain instrumentation -output for black-box, closed-source binary code snippets. This mechanism -can be then used by afl-fuzz to stress-test targets that couldn't be built +output for black-box, closed-source binary code snippets. This mechanism +can be then used by afl-fuzz to stress-test targets that couldn't be built with afl-cc or used in QEMU mode. There is a significant performance penalty compared to native AFL, @@ -25,7 +26,7 @@ For some pointers for more advanced emulation, take a look at [BaseSAFE](https:/ ### Building AFL++'s Unicorn Mode First, make AFL++ as usual. -Once that completes successfully you need to build and add in the Unicorn Mode +Once that completes successfully you need to build and add in the Unicorn Mode features: ``` @@ -33,10 +34,10 @@ cd unicorn_mode ./build_unicorn_support.sh ``` -NOTE: This script checks out a Unicorn Engine fork as submodule that has been tested -and is stable-ish, based on the unicorn engine `next` branch. +NOTE: This script checks out a Unicorn Engine fork as submodule that has been tested +and is stable-ish, based on the unicorn engine `next` branch. -Building Unicorn will take a little bit (~5-10 minutes). Once it completes +Building Unicorn will take a little bit (~5-10 minutes). Once it completes it automatically compiles a sample application and verifies that it works. ### Fuzzing with Unicorn Mode @@ -46,25 +47,24 @@ To use unicorn-mode effectively you need to prepare the following: * Relevant binary code to be fuzzed * Knowledge of the memory map and good starting state * Folder containing sample inputs to start fuzzing with - + Same ideas as any other AFL inputs - + Quality/speed of results will depend greatly on the quality of starting + + Same ideas as any other AFL++ inputs + + Quality/speed of results will depend greatly on the quality of starting samples + See AFL's guidance on how to create a sample corpus * Unicornafl-based test harness in Rust, C, or Python, which: + Adds memory map regions - + Loads binary code into memory + + Loads binary code into memory + Calls uc.afl_fuzz() / uc.afl_start_forkserver + Loads and verifies data to fuzz from a command-line specified file - + AFL will provide mutated inputs by changing the file passed to + + AFL++ will provide mutated inputs by changing the file passed to the test harness + Presumably the data to be fuzzed is at a fixed buffer address - + If input constraints (size, invalid bytes, etc.) are known they - should be checked in the place_input handler. If a constraint - fails, just return false from the handler. AFL will treat the input as - 'uninteresting' and move on. + + If input constraints (size, invalid bytes, etc.) are known they + should be checked in the place_input handler. If a constraint + fails, just return false from the handler. AFL++ will treat the input as 'uninteresting' and move on. + Sets up registers and memory state for beginning of test + Emulates the interesting code from beginning to end - + If a crash is detected, the test harness must 'crash' by + + If a crash is detected, the test harness must 'crash' by throwing a signal (SIGSEGV, SIGKILL, SIGABORT, etc.), or indicate a crash in the crash validation callback. Once you have all those things ready to go you just need to run afl-fuzz in @@ -77,14 +77,13 @@ afl-fuzz -U -m none -i /path/to/inputs -o /path/to/results -- ./test_harness @@ The normal afl-fuzz command line format applies to everything here. Refer to AFL's main documentation for more info about how to use afl-fuzz effectively. -For a much clearer vision of what all of this looks like, please refer to the -sample provided in the 'unicorn_mode/samples' directory. There is also a blog -post that uses slightly older concepts, but describes the general ideas, at: +For a much clearer vision of what all of this looks like, refer to the sample +provided in the 'unicorn_mode/samples' directory. There is also a blog post that +uses slightly older concepts, but describes the general ideas, at: [https://medium.com/@njvoss299/afl-unicorn-fuzzing-arbitrary-binary-code-563ca28936bf](https://medium.com/@njvoss299/afl-unicorn-fuzzing-arbitrary-binary-code-563ca28936bf) - -The ['helper_scripts'](./helper_scripts) directory also contains several helper scripts that allow you +The ['helper_scripts'](./helper_scripts) directory also contains several helper scripts that allow you to dump context from a running process, load it, and hook heap allocations. For details on how to use this check out the follow-up blog post to the one linked above. @@ -105,8 +104,8 @@ Comparison instructions are currently instrumented only for the x86, x86_64 and ## 4) Gotchas, feedback, bugs -Running the build script builds Unicornafl and its python bindings and installs -them on your system. +Running the build script builds Unicornafl and its python bindings and installs +them on your system. This installation will leave any existing Unicorn installations untouched. If you want to use unicornafl instead of unicorn in a script, replace all `unicorn` imports with `unicornafl` inputs, everything else should "just work". diff --git a/unicorn_mode/samples/c/COMPILE.md b/unicorn_mode/samples/c/COMPILE.md index 7da140f7..e5265071 100644 --- a/unicorn_mode/samples/c/COMPILE.md +++ b/unicorn_mode/samples/c/COMPILE.md @@ -6,6 +6,7 @@ This shows a simple harness for unicornafl in C The target can be built using the `make` command. Just make sure you have built unicorn support first: + ```bash cd /path/to/afl/unicorn_mode ./build_unicorn_support.sh @@ -19,4 +20,4 @@ was built in case you want to rebuild it or recompile it for any reason. The pre-built binary (persistent_target_x86_64) was built using -g -O0 in gcc. -We then load the binary and execute the main function directly. +Then load the binary and execute the main function directly. diff --git a/unicorn_mode/samples/persistent/COMPILE.md b/unicorn_mode/samples/persistent/COMPILE.md index 9f2ae718..5e607aef 100644 --- a/unicorn_mode/samples/persistent/COMPILE.md +++ b/unicorn_mode/samples/persistent/COMPILE.md @@ -3,7 +3,7 @@ This shows a simple persistent harness for unicornafl in C. In contrast to the normal c harness, this harness manually resets the unicorn state on each new input. -Thanks to this, we can rerun the test case in unicorn multiple times, without +Thanks to this, you can rerun the test case in unicorn multiple times, without the need to fork again. ## Compiling sample.c @@ -25,4 +25,4 @@ was built in case you want to rebuild it or recompile it for any reason. The pre-built binary (persistent_target_x86_64.bin) was built using -g -O0 in gcc. -We then load the binary and we execute the main function directly.
\ No newline at end of file +Then load the binary and execute the main function directly.
\ No newline at end of file diff --git a/unicorn_mode/samples/speedtest/README.md b/unicorn_mode/samples/speedtest/README.md index 3c1184a2..bd5ba8d0 100644 --- a/unicorn_mode/samples/speedtest/README.md +++ b/unicorn_mode/samples/speedtest/README.md @@ -35,7 +35,6 @@ cd python TODO: add results here. - ## Compiling speedtest_target.c You shouldn't need to compile simple_target.c since a X86_64 binary version is @@ -44,22 +43,30 @@ was built in case you want to rebuild it or recompile it for any reason. The pre-built binary (simple_target_x86_64.bin) was built using -g -O0 in gcc. -We then load the binary and execute the main function directly. +Then load the binary and execute the main function directly. + +## Addresses for the harness -## Addresses for the harness: To find the address (in hex) of main, run: + ```bash objdump -M intel -D target | grep '<main>:' | cut -d" " -f1 ``` + To find all call sites to magicfn, run: + ```bash objdump -M intel -D target | grep '<magicfn>$' | cut -d":" -f1 ``` + For malloc callsites: + ```bash objdump -M intel -D target | grep '<malloc@plt>$' | cut -d":" -f1 ``` + And free callsites: + ```bash objdump -M intel -D target | grep '<free@plt>$' | cut -d":" -f1 -``` +```
\ No newline at end of file diff --git a/utils/README.md b/utils/README.md index b8df0b47..debc86e8 100644 --- a/utils/README.md +++ b/utils/README.md @@ -13,10 +13,10 @@ Here's a quick overview of the stuff you can find in this directory: - afl_proxy - skeleton file example to show how to fuzz something where you gather coverage data via - different means, e.g. hw debugger + different means, e.g., hw debugger - afl_untracer - fuzz binary-only libraries much faster but with - less coverage than qemu_mode + less coverage than QEMU mode - analysis_scripts - random -o out analysis scripts @@ -48,7 +48,7 @@ Here's a quick overview of the stuff you can find in this directory: - defork - intercept fork() in targets - distributed_fuzzing - a sample script for synchronizing fuzzer instances - across multiple machines (see parallel_fuzzing.md). + across multiple machines. - libdislocator - like ASAN but lightweight. diff --git a/utils/afl_network_proxy/README.md b/utils/afl_network_proxy/README.md index 05659c45..c34463e2 100644 --- a/utils/afl_network_proxy/README.md +++ b/utils/afl_network_proxy/README.md @@ -1,12 +1,13 @@ # afl-network-proxy -If you want to run afl-fuzz over the network than this is what you need :) +If you want to run afl-fuzz over the network, then this is what you need. :) Note that the impact on fuzzing speed will be huge, expect a loss of 90%. ## When to use this 1. when you have to fuzz a target that has to run on a system that cannot - contain the fuzzing output (e.g. /tmp too small and file system is read-only) + contain the fuzzing output (e.g., /tmp too small and file system is + read-only) 2. when the target instantly reboots on crashes 3. ... any other reason you would need this @@ -28,32 +29,34 @@ For most targets this hurts performance though so it is disabled by default. Run `afl-network-server` with your target with the -m and -t values you need. Important is the -i parameter which is the TCP port to listen on. e.g.: + ``` afl-network-server -i 1111 -m 25M -t 1000 -- /bin/target -f @@ ``` ### on the (afl-fuzz) main node -Just run afl-fuzz with your normal options, however the target should be +Just run afl-fuzz with your normal options, however, the target should be `afl-network-client` with the IP and PORT of the `afl-network-server` and increase the -t value: + ``` afl-fuzz -i in -o out -t 2000+ -- afl-network-client TARGET-IP 1111 ``` -Note the '+' on the -t parameter value. The afl-network-server will take -care of proper timeouts hence afl-fuzz should not. The '+' increases the -timeout and the value itself should be 500-1000 higher than the one on -afl-network-server. + +Note the '+' on the -t parameter value. The afl-network-server will take care of +proper timeouts hence afl-fuzz should not. The '+' increases the timeout and the +value itself should be 500-1000 higher than the one on afl-network-server. ### networking The TARGET can be an IPv4 or IPv6 address, or a host name that resolves to either. Note that also the outgoing interface can be specified with a '%' for -`afl-network-client`, e.g. `fe80::1234%eth0`. +`afl-network-client`, e.g., `fe80::1234%eth0`. Also make sure your default TCP window size is larger than your MAP_SIZE (130kb is a good value). -On Linux that is the middle value of `/proc/sys/net/ipv4/tcp_rmem` +On Linux that is the middle value of `/proc/sys/net/ipv4/tcp_rmem` ## how to compile and install diff --git a/utils/afl_untracer/README.md b/utils/afl_untracer/README.md index ada0c916..da0e0c77 100644 --- a/utils/afl_untracer/README.md +++ b/utils/afl_untracer/README.md @@ -5,9 +5,9 @@ afl-untracer is an example skeleton file which can easily be used to fuzz a closed source library. -It requires less memory and is x3-5 faster than qemu_mode however it is way -more course grained and does not provide interesting features like compcov -or cmplog. +It requires less memory and is x3-5 faster than QEMU mode, however, it is way +more course grained and does not provide interesting features like compcov or +cmplog. Supported is so far Intel (i386/x86_64) and AARCH64. @@ -15,7 +15,7 @@ Supported is so far Intel (i386/x86_64) and AARCH64. ### Modify afl-untracer.c -Read and modify afl-untracer.c then `make`. +Read and modify afl-untracer.c, then `make`. To adapt afl-untracer.c to your needs, read the header of the file and then search and edit the `STEP 1`, `STEP 2` and `STEP 3` locations. @@ -28,28 +28,34 @@ To generate the `patches.txt` file for your target library use the The patches.txt file has to be pointed to by `AFL_UNTRACER_FILE`. To easily run the scripts without needing to run the GUI with Ghidra: + ``` /opt/ghidra/support/analyzeHeadless /tmp/ tmp$$ -import libtestinstr.so -postscript ./ghidra_get_patchpoints.java rm -rf /tmp/tmp$$ ``` + The file is created at `~/Desktop/patches.txt` ### Fuzzing Example (after modifying afl-untracer.c to your needs, compiling and creating patches.txt): + ``` LD_LIBRARY_PATH=/path/to/target/library AFL_UNTRACER_FILE=./patches.txt afl-fuzz -i in -o out -- ./afl-untracer ``` + (or even remote via afl-network-proxy). ### Testing and debugging For testing/debugging you can try: + ``` make DEBUG=1 AFL_UNTRACER_FILE=./patches.txt AFL_DEBUG=1 gdb ./afl-untracer ``` + and then you can easily set breakpoints to "breakpoint" and "fuzz". # Background @@ -57,4 +63,4 @@ and then you can easily set breakpoints to "breakpoint" and "fuzz". This idea is based on [UnTracer](https://github.com/FoRTE-Research/UnTracer-AFL) and modified by [Trapfuzz](https://github.com/googleprojectzero/p0tools/tree/master/TrapFuzz). This implementation is slower because the traps are not patched out with each -run, but on the other hand gives much better coverage information. +run, but on the other hand gives much better coverage information.
\ No newline at end of file diff --git a/utils/aflpp_driver/README.md b/utils/aflpp_driver/README.md index 4560be2b..c547aaea 100644 --- a/utils/aflpp_driver/README.md +++ b/utils/aflpp_driver/README.md @@ -5,27 +5,27 @@ aflpp_driver is used to compile directly libfuzzer `LLVMFuzzerTestOneInput()` targets. -Just do `afl-clang-fast++ -o fuzz fuzzer_harness.cc libAFLDriver.a [plus required linking]`. +Just do `afl-clang-fast++ -o fuzz fuzzer_harness.cc libAFLDriver.a [plus +required linking]`. -You can also sneakily do this little trick: -If this is the clang compile command to build for libfuzzer: - `clang++ -o fuzz -fsanitize=fuzzer fuzzer_harness.cc -lfoo` -then just switch `clang++` with `afl-clang-fast++` and our compiler will +You can also sneakily do this little trick: If this is the clang compile command +to build for libfuzzer: `clang++ -o fuzz -fsanitize=fuzzer fuzzer_harness.cc +-lfoo`, then just switch `clang++` with `afl-clang-fast++` and our compiler will magically insert libAFLDriver.a :) -To use shared-memory test cases, you need nothing to do. -To use stdin test cases, give `-` as the only command line parameter. -To use file input test cases, give `@@` as the only command line parameter. +To use shared-memory test cases, you need nothing to do. To use stdin test +cases, give `-` as the only command line parameter. To use file input test +cases, give `@@` as the only command line parameter. -IMPORTANT: if you use `afl-cmin` or `afl-cmin.bash` then either pass `-` -or `@@` as command line parameters. +IMPORTANT: if you use `afl-cmin` or `afl-cmin.bash`, then either pass `-` or +`@@` as command line parameters. ## aflpp_qemu_driver -Note that you can use the driver too for frida_mode (`-O`). +Note that you can use the driver too for FRIDA mode (`-O`). aflpp_qemu_driver is used for libfuzzer `LLVMFuzzerTestOneInput()` targets that -are to be fuzzed in qemu_mode. So we compile them with clang/clang++, without +are to be fuzzed in QEMU mode. So compile them with clang/clang++, without -fsantize=fuzzer or afl-clang-fast, and link in libAFLQemuDriver.a: `clang++ -o fuzz fuzzer_harness.cc libAFLQemuDriver.a [plus required linking]`. @@ -38,6 +38,6 @@ AFL_QEMU_PERSISTENT_HOOK=/path/to/aflpp_qemu_driver_hook.so afl-fuzz -Q ... -- . ``` if you use afl-cmin or `afl-showmap -C` with the aflpp_qemu_driver you need to -set the set same AFL_QEMU_... (or AFL_FRIDA_...) environment variables. -If you want to use afl-showmap (without -C) or afl-cmin.bash then you may not -set these environment variables and rather set `AFL_QEMU_DRIVER_NO_HOOK=1`.
\ No newline at end of file +set the set same AFL_QEMU_... (or AFL_FRIDA_...) environment variables. If you +want to use afl-showmap (without -C) or afl-cmin.bash, then you may not set +these environment variables and rather set `AFL_QEMU_DRIVER_NO_HOOK=1`.
\ No newline at end of file diff --git a/utils/argv_fuzzing/README.md b/utils/argv_fuzzing/README.md index 192d72f7..e9224995 100644 --- a/utils/argv_fuzzing/README.md +++ b/utils/argv_fuzzing/README.md @@ -1,6 +1,6 @@ # argvfuzz -AFL supports fuzzing file inputs or stdin. When source is available, +AFL++ supports fuzzing file inputs or stdin. When source is available, `argv-fuzz-inl.h` can be used to change `main()` to build argv from stdin. `argvfuzz` tries to provide the same functionality for binaries. When loaded @@ -13,4 +13,4 @@ A few conditions need to be fulfilled for this mechanism to work correctly: 2. If the target binary does not use the default libc's `_start` implementation (crt1.o), the hook may not run. 3. The hook will replace argv with pointers to `.data` of `argvfuzz.so`. If the - target binary expects argv to be living on the stack, things may go wrong. + target binary expects argv to be living on the stack, things may go wrong.
\ No newline at end of file diff --git a/utils/autodict_ql/readme.md b/utils/autodict_ql/readme.md index 9170f552..f61026b7 100644 --- a/utils/autodict_ql/readme.md +++ b/utils/autodict_ql/readme.md @@ -2,21 +2,35 @@ ## What is this? -`Autodict-QL` is a plugin system that enables fast generation of Tokens/Dictionaries in a handy way that can be manipulated by the user (unlike The LLVM Passes that are hard to modify). This means that autodict-ql is a scriptable feature which basically uses CodeQL (a powerful semantic code analysis engine) to fetch information from a code base. +`Autodict-QL` is a plugin system that enables fast generation of +Tokens/Dictionaries in a handy way that can be manipulated by the user (unlike +The LLVM Passes that are hard to modify). This means that autodict-ql is a +scriptable feature which basically uses CodeQL (a powerful semantic code +analysis engine) to fetch information from a code base. -Tokens are useful when you perform fuzzing on different parsers. The AFL++ `-x` switch enables the usage of dictionaries through your fuzzing campaign. If you are not familiar with Dictionaries in fuzzing, take a look [here](https://github.com/AFLplusplus/AFLplusplus/tree/stable/dictionaries) . +Tokens are useful when you perform fuzzing on different parsers. The AFL++ `-x` +switch enables the usage of dictionaries through your fuzzing campaign. If you +are not familiar with Dictionaries in fuzzing, take a look +[here](https://github.com/AFLplusplus/AFLplusplus/tree/stable/dictionaries). +## Why CodeQL? -## Why CodeQL ? -We basically developed this plugin on top of the CodeQL engine because it gives the user scripting features, it's easier and it's independent of the LLVM system. This means that a user can write his CodeQL scripts or modify the current scripts to improve or change the token generation algorithms based on different program analysis concepts. - +We basically developed this plugin on top of the CodeQL engine because it gives +the user scripting features, it's easier and it's independent of the LLVM +system. This means that a user can write his CodeQL scripts or modify the +current scripts to improve or change the token generation algorithms based on +different program analysis concepts. ## CodeQL scripts -Currently, we pushed some scripts as defaults for Token generation. In addition, we provide every CodeQL script as an standalone script because it's easier to modify or test. -Currently we provided the following CodeQL scripts : +Currently, we pushed some scripts as defaults for Token generation. In addition, +we provide every CodeQL script as an standalone script because it's easier to +modify or test. + +Currently we provided the following CodeQL scripts: -`strcmp-str.ql` is used to extract strings that are related to the `strcmp` function. +`strcmp-str.ql` is used to extract strings that are related to the `strcmp` +function. `strncmp-str.ql` is used to extract the strings from the `strncmp` function. @@ -24,77 +38,110 @@ Currently we provided the following CodeQL scripts : `litool.ql` extracts Magic numbers as Hexadecimal format. -`strtool.ql` extracts strings with uses of a regex and dataflow concept to capture the string comparison functions. If `strcmp` is rewritten in a project as Mystrcmp or something like strmycmp, then this script can catch the arguments and these are valuable tokens. - -You can write other CodeQL scripts to extract possible effective tokens if you think they can be useful. +`strtool.ql` extracts strings with uses of a regex and dataflow concept to +capture the string comparison functions. If `strcmp` is rewritten in a project +as Mystrcmp or something like strmycmp, then this script can catch the arguments +and these are valuable tokens. +You can write other CodeQL scripts to extract possible effective tokens if you +think they can be useful. ## Usage -Before you proceed to installation make sure that you have the following packages by installing them : -```shell -sudo apt install build-essential libtool-bin python3-dev python3 automake git vim wget -y -``` -The usage of Autodict-QL is pretty easy. But let's describe it as: +Before you proceed to installation make sure that you have the following +packages by installing them: -1. First of all, you need to have CodeQL installed on the system. we make this possible with `build-codeql.sh` bash script. This script will install CodeQL completety and will set the required environment variables for your system. -Do the following : ```shell -# chmod +x codeql-build.sh -# ./codeql-build.sh -# source ~/.bashrc -# codeql +sudo apt install build-essential libtool-bin python3-dev python3 automake git vim wget -y ``` -Then you should get: -```shell -Usage: codeql <command> <argument>... -Create and query CodeQL databases, or work with the QL language. - -GitHub makes this program freely available for the analysis of open-source software and certain other uses, but it is -not itself free software. Type codeql --license to see the license terms. - - --license Show the license terms for the CodeQL toolchain. -Common options: - -h, --help Show this help text. - -v, --verbose Incrementally increase the number of progress messages printed. - -q, --quiet Incrementally decrease the number of progress messages printed. -Some advanced options have been hidden; try --help -v for a fuller view. -Commands: - query Compile and execute QL code. - bqrs Get information from .bqrs files. - database Create, analyze and process CodeQL databases. - dataset [Plumbing] Work with raw QL datasets. - test Execute QL unit tests. - resolve [Deep plumbing] Helper commands to resolve disk locations etc. - execute [Deep plumbing] Low-level commands that need special JVM options. - version Show the version of the CodeQL toolchain. - generate Generate formatted QL documentation. - github Commands useful for interacting with the GitHub API through CodeQL. -``` +The usage of Autodict-QL is pretty easy. But let's describe it as: -2. Compile your project with CodeQL: For using the Autodict-QL plugin, you need to compile the source of the target you want to fuzz with CodeQL. This is not something hard. - - First you need to create a CodeQL database of the project codebase, suppose we want to compile `libxml` with codeql. Go to libxml and issue the following commands: - - `./configure --disable-shared` - - `codeql create database libxml-db --language=cpp --command=make` - - Now you have the CodeQL database of the project :-) -3. The final step is to update the CodeQL database you created in step 2 (Suppose we are in `aflplusplus/utils/autodict_ql/` directory): - - `codeql database upgrade /home/user/libxml/libxml-db` +1. First of all, you need to have CodeQL installed on the system. We make this + possible with `build-codeql.sh` bash script. This script will install CodeQL + completety and will set the required environment variables for your system. + Do the following: + + ```shell + # chmod +x codeql-build.sh + # ./codeql-build.sh + # source ~/.bashrc + # codeql + ``` + + Then you should get: + + ```shell + Usage: codeql <command> <argument>... + Create and query CodeQL databases, or work with the QL language. + + GitHub makes this program freely available for the analysis of open-source software and certain other uses, but it is + not itself free software. Type codeql --license to see the license terms. + + --license Show the license terms for the CodeQL toolchain. + Common options: + -h, --help Show this help text. + -v, --verbose Incrementally increase the number of progress messages printed. + -q, --quiet Incrementally decrease the number of progress messages printed. + Some advanced options have been hidden; try --help -v for a fuller view. + Commands: + query Compile and execute QL code. + bqrs Get information from .bqrs files. + database Create, analyze and process CodeQL databases. + dataset [Plumbing] Work with raw QL datasets. + test Execute QL unit tests. + resolve [Deep plumbing] Helper commands to resolve disk locations etc. + execute [Deep plumbing] Low-level commands that need special JVM options. + version Show the version of the CodeQL toolchain. + generate Generate formatted QL documentation. + github Commands useful for interacting with the GitHub API through CodeQL. + ``` + +2. Compile your project with CodeQL: For using the Autodict-QL plugin, you need + to compile the source of the target you want to fuzz with CodeQL. This is not + something hard. + - First you need to create a CodeQL database of the project codebase, suppose + we want to compile `libxml` with codeql. Go to libxml and issue the + following commands: + - `./configure --disable-shared` + - `codeql create database libxml-db --language=cpp --command=make` + - Now you have the CodeQL database of the project :-) +3. The final step is to update the CodeQL database you created in step 2 + (Suppose we are in `aflplusplus/utils/autodict_ql/` directory): + - `codeql database upgrade /home/user/libxml/libxml-db` 4. Everything is set! Now you should issue the following to get the tokens: - - `python3 autodict-ql.py [CURRECT_DIR] [CODEQL_DATABASE_PATH] [TOKEN_PATH]` - - example : `python3 /home/user/AFLplusplus/utils/autodict_ql/autodict-ql.py $PWD /home/user/libxml/libxml-db tokens` - - This will create the final `tokens` dir for you and you are done, then pass the tokens path to AFL++'s `-x` flag. -5. Done! - + - `python3 autodict-ql.py [CURRECT_DIR] [CODEQL_DATABASE_PATH] [TOKEN_PATH]` + - example: `python3 /home/user/AFLplusplus/utils/autodict_ql/autodict-ql.py + $PWD /home/user/libxml/libxml-db tokens` + - This will create the final `tokens` dir for you and you are done, then + pass the tokens path to AFL++'s `-x` flag. +5. Done! ## More on dictionaries and tokens -Core developer of the AFL++ project Marc Heuse also developed a similar tool named `dict2file` which is a LLVM pass which can automatically extract useful tokens, in addition with LTO instrumentation mode, this dict2file is automatically generates token extraction. `Autodict-QL` plugin gives you scripting capability and you can do whatever you want to extract from the Codebase and it's up to you. In addition it's independent from LLVM system. -On the other hand, you can also use Google dictionaries which have been made public in May 2020, but the problem of using Google dictionaries is that they are limited to specific file formats and specifications. For example, for testing binutils and ELF file format or AVI in FFMPEG, there are no prebuilt dictionaries, so it is highly recommended to use `Autodict-QL` or `Dict2File` features to automatically generate dictionaries based on the target. - -I've personally prefered to use `Autodict-QL` or `dict2file` rather than Google dictionaries or any other manually generated dictionaries as `Autodict-QL` and `dict2file` are working based on the target. -In overall, fuzzing with dictionaries and well-generated tokens will give better results. - -There are 2 important points to remember : -- If you combine `Autodict-QL` with AFL++ cmplog, you will get much better code coverage and hence better chances to discover new bugs. -- Do not forget to set `AFL_MAX_DET_EXTRAS` at least to the number of generated dictionaries. If you forget to set this environment variable, then AFL++ uses just 200 tokens and use the rest of them only probabilistically. So this will guarantee that your tokens will be used by AFL++. +Core developer of the AFL++ project Marc Heuse also developed a similar tool +named `dict2file` which is a LLVM pass which can automatically extract useful +tokens, in addition with LTO instrumentation mode, this dict2file is +automatically generates token extraction. `Autodict-QL` plugin gives you +scripting capability and you can do whatever you want to extract from the +Codebase and it's up to you. In addition it's independent from LLVM system. On +the other hand, you can also use Google dictionaries which have been made public +in May 2020, but the problem of using Google dictionaries is that they are +limited to specific file formats and specifications. For example, for testing +binutils and ELF file format or AVI in FFMPEG, there are no pre-built +dictionaries, so it is highly recommended to use `Autodict-QL` or `Dict2File` +features to automatically generate dictionaries based on the target. + +I've personally preferred to use `Autodict-QL` or `dict2file` rather than Google +dictionaries or any other manually generated dictionaries as `Autodict-QL` and +`dict2file` are working based on the target. In overall, fuzzing with +dictionaries and well-generated tokens will give better results. + +There are 2 important points to remember: + +- If you combine `Autodict-QL` with AFL++ cmplog, you will get much better code + coverage and hence better chances to discover new bugs. +- Do not forget to set `AFL_MAX_DET_EXTRAS` at least to the number of generated + dictionaries. If you forget to set this environment variable, then AFL++ uses + just 200 tokens and use the rest of them only probabilistically. So this will + guarantee that your tokens will be used by AFL++.
\ No newline at end of file diff --git a/utils/libdislocator/README.md b/utils/libdislocator/README.md index d0340af0..7150c205 100644 --- a/utils/libdislocator/README.md +++ b/utils/libdislocator/README.md @@ -10,8 +10,8 @@ heap-related security bugs in several ways: subsequent PROT_NONE page, causing most off-by-one reads and writes to immediately segfault, - - It adds a canary immediately below the allocated buffer, to catch writes - to negative offsets (won't catch reads, though), + - It adds a canary immediately below the allocated buffer, to catch writes to + negative offsets (won't catch reads, though), - It sets the memory returned by malloc() to garbage values, improving the odds of crashing when the target accesses uninitialized data, @@ -19,37 +19,36 @@ heap-related security bugs in several ways: - It sets freed memory to PROT_NONE and does not actually reuse it, causing most use-after-free bugs to segfault right away, - - It forces all realloc() calls to return a new address - and sets - PROT_NONE on the original block. This catches use-after-realloc bugs, + - It forces all realloc() calls to return a new address - and sets PROT_NONE + on the original block. This catches use-after-realloc bugs, - - It checks for calloc() overflows and can cause soft or hard failures - of alloc requests past a configurable memory limit (AFL_LD_LIMIT_MB, + - It checks for calloc() overflows and can cause soft or hard failures of + alloc requests past a configurable memory limit (AFL_LD_LIMIT_MB, AFL_LD_HARD_FAIL). - Optionally, in platforms supporting it, huge pages can be used by passing USEHUGEPAGE=1 to make. - - - Size alignment to `max_align_t` can be enforced with AFL_ALIGNED_ALLOC=1. - In this case, a tail canary is inserted in the padding bytes at the end - of the allocated zone. This reduce the ability of libdislocator to detect + + - Size alignment to `max_align_t` can be enforced with AFL_ALIGNED_ALLOC=1. In + this case, a tail canary is inserted in the padding bytes at the end of the + allocated zone. This reduce the ability of libdislocator to detect off-by-one bugs but also it make slibdislocator compliant to the C standard. Basically, it is inspired by some of the non-default options available for the OpenBSD allocator - see malloc.conf(5) on that platform for reference. It is -also somewhat similar to several other debugging libraries, such as gmalloc -and DUMA - but is simple, plug-and-play, and designed specifically for fuzzing -jobs. +also somewhat similar to several other debugging libraries, such as gmalloc and +DUMA - but is simple, plug-and-play, and designed specifically for fuzzing jobs. Note that it does nothing for stack-based memory handling errors. The -fstack-protector-all setting for GCC / clang, enabled when using AFL_HARDEN, can catch some subset of that. The allocator is slow and memory-intensive (even the tiniest allocation uses up -4 kB of physical memory and 8 kB of virtual mem), making it completely unsuitable -for "production" uses; but it can be faster and more hassle-free than ASAN / MSAN -when fuzzing small, self-contained binaries. +4 kB of physical memory and 8 kB of virtual mem), making it completely +unsuitable for "production" uses; but it can be faster and more hassle-free than +ASAN / MSAN when fuzzing small, self-contained binaries. -To use this library, run AFL like so: +To use this library, run AFL++ like so: ``` AFL_PRELOAD=/path/to/libdislocator.so ./afl-fuzz [...other params...] @@ -62,7 +61,7 @@ Similarly to afl-tmin, the library is not "proprietary" and can be used with other fuzzers or testing tools without the need for any code tweaks. It does not require AFL-instrumented binaries to work. -Note that the AFL_PRELOAD approach (which AFL internally maps to LD_PRELOAD or +Note that the AFL_PRELOAD approach (which AFL++ internally maps to LD_PRELOAD or DYLD_INSERT_LIBRARIES, depending on the OS) works only if the target binary is dynamically linked. Otherwise, attempting to use the library will have no -effect. +effect.
\ No newline at end of file diff --git a/utils/libtokencap/README.md b/utils/libtokencap/README.md index a39ed3a5..343fcce0 100644 --- a/utils/libtokencap/README.md +++ b/utils/libtokencap/README.md @@ -40,10 +40,10 @@ when using afl-gcc. This setting specifically adds the following flags: -fno-builtin-strcasestr ``` -The next step is simply loading this library via LD_PRELOAD. The optimal usage -pattern is to allow afl-fuzz to fuzz normally for a while and build up a corpus, -and then fire off the target binary, with libtokencap.so loaded, on every file -found by AFL in that earlier run. This demonstrates the basic principle: +The next step is to load this library via LD_PRELOAD. The optimal usage pattern +is to allow afl-fuzz to fuzz normally for a while and build up a corpus, and +then fire off the target binary, with libtokencap.so loaded, on every file found +by AFL++ in that earlier run. This demonstrates the basic principle: ``` export AFL_TOKEN_FILE=$PWD/temp_output.txt diff --git a/utils/optimin/README.md b/utils/optimin/README.md index c6f2af06..340022b8 100644 --- a/utils/optimin/README.md +++ b/utils/optimin/README.md @@ -73,11 +73,11 @@ and `WEIGHT_N` is an integer weight. ## Further Details and Citation -For more details, please see the paper [Seed Selection for Successful -Fuzzing](https://dl.acm.org/doi/10.1145/3460319.3464795). If you use OptiMin in -your research, please cite this paper. +For more details, see the paper +[Seed Selection for Successful Fuzzing](https://dl.acm.org/doi/10.1145/3460319.3464795). +If you use OptiMin in your research, please cite this paper. -Bibtex: +BibTeX: ```bibtex @inproceedings{Herrera:2021:FuzzSeedSelection, @@ -91,4 +91,4 @@ Bibtex: location = {Virtual, Denmark}, publisher = {Association for Computing Machinery}, } -``` +```
\ No newline at end of file diff --git a/utils/qbdi_mode/README.md b/utils/qbdi_mode/README.md index 8b768906..08558017 100755 --- a/utils/qbdi_mode/README.md +++ b/utils/qbdi_mode/README.md @@ -2,14 +2,13 @@ NOTE: this code is outdated and first would need to be adapted to the current AFL++ versions. -Try frida_mode or fpicker [https://github.com/ttdennis/fpicker/](https://github.com/ttdennis/fpicker/) first, maybe they suite your need. +Try FRIDA mode or fpicker [https://github.com/ttdennis/fpicker/](https://github.com/ttdennis/fpicker/) first, maybe they suite your need. ## 1) Introduction The code in ./qbdi_mode allows you to build a standalone feature that using the QBDI framework to fuzz android native library. - ## 2) Build First download the Android NDK @@ -34,7 +33,9 @@ For x86 standalone-toolchain ./build/tools/make_standalone_toolchain.py --arch x86 --api 21 --install-dir ../android-standalone-toolchain-x86 ``` -In alternative you can also use the prebuilt toolchain, in that case make sure to set the proper CC and CXX env variables because there are many different compilers for each API version in the prebuilt toolchain. +In alternative you can also use the pre-built toolchain, in that case make sure +to set the proper CC and CXX environment variables because there are many +different compilers for each API version in the pre-built toolchain. For example: @@ -51,6 +52,7 @@ https://qbdi.quarkslab.com/ ``` For Android x86_64 + ``` https://github.com/QBDI/QBDI/releases/download/v0.7.0/QBDI-0.7.0-android-X86_64.tar.gz ``` @@ -64,7 +66,7 @@ cd android-qbdi-sdk-x86_64/ tar xvf QBDI-0.7.0-android-X86_64.tar.gz ``` -Now set the `STANDALONE_TOOLCHAIN_PATH` to the path of standalone-toolchain +Now set the `STANDALONE_TOOLCHAIN_PATH` to the path of standalone-toolchain ``` export STANDALONE_TOOLCHAIN_PATH=/home/hac425/workspace/android-standalone-toolchain-x86_64 @@ -84,7 +86,6 @@ Then run the build.sh this could build the afl-fuzz and also the qbdi template for android x86_64 - ### Example The demo-so.c is an vulnerable library, it has a function for test @@ -127,9 +128,10 @@ int target_func(char *buf, int size) { } ``` -This could be build to `libdemo.so`. +This could be built to `libdemo.so`. + +Then load the library in template.cpp and find the `target` function address: -Then we should load the library in template.cpp and find the `target` function address. ```c void *handle = dlopen(lib_path, RTLD_LAZY); .......................................... @@ -138,7 +140,7 @@ Then we should load the library in template.cpp and find the `target` function a p_target_func = (target_func)dlsym(handle, "target_func"); ``` -then we read the data from file and call the function in `fuzz_func` +Then read the data from file and call the function in `fuzz_func`: ```c QBDI_NOINLINE int fuzz_func() { @@ -157,6 +159,7 @@ QBDI_NOINLINE int fuzz_func() { ``` Just compile it + ``` ./build.sh x86_64 ``` @@ -173,6 +176,7 @@ adb push ../../android-standalone-toolchain-x86_64/sysroot/usr/lib/x86_64-linux- ``` In android adb shell, run the loader to test if it runs + ``` cd /data/local/tmp export LD_LIBRARY_PATH=/data/local/tmp @@ -199,5 +203,4 @@ Now run `afl-fuzz` to fuzz the demo library ./afl-fuzz -i in -o out -- ./loader /data/local/tmp/libdemo.so @@ ``` - - +
\ No newline at end of file diff --git a/utils/qemu_persistent_hook/README.md b/utils/qemu_persistent_hook/README.md index 3f908c22..3bbaef6b 100644 --- a/utils/qemu_persistent_hook/README.md +++ b/utils/qemu_persistent_hook/README.md @@ -16,4 +16,4 @@ mkdir in echo 0000 > in/in ../../afl-fuzz -Q -i in -o out -- ./test -``` +```
\ No newline at end of file |