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| -rw-r--r-- | CONTRIBUTING.md | 11 | ||||
| -rw-r--r-- | README.md | 26 | ||||
| -rw-r--r-- | TODO.md | 9 | ||||
| -rw-r--r-- | docs/FAQ.md | 82 | ||||
| -rw-r--r-- | docs/INSTALL.md | 79 | ||||
| -rw-r--r-- | docs/afl-fuzz_approach.md | 4 | ||||
| -rw-r--r-- | docs/best_practices.md | 114 | ||||
| -rw-r--r-- | docs/custom_mutators.md | 80 | ||||
| -rw-r--r-- | docs/env_variables.md | 96 | ||||
| -rw-r--r-- | docs/fuzzing_binary-only_targets.md | 6 | ||||
| -rw-r--r-- | docs/fuzzing_in_depth.md | 50 | ||||
| -rw-r--r-- | docs/ideas.md | 55 | ||||
| -rw-r--r-- | docs/important_changes.md | 29 | ||||
| -rw-r--r-- | docs/rpc_statsd.md | 73 | ||||
| -rw-r--r-- | frida_mode/Scripting.md | 20 | ||||
| -rw-r--r-- | instrumentation/README.gcc_plugin.md | 4 |
16 files changed, 435 insertions, 303 deletions
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md index 0ab4f8ec..fb13b91a 100644 --- a/CONTRIBUTING.md +++ b/CONTRIBUTING.md @@ -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 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. +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 diff --git a/README.md b/README.md index 08363149..b70eb1ab 100644 --- a/README.md +++ b/README.md @@ -44,8 +44,8 @@ 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 +53,8 @@ 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). @@ -120,8 +120,8 @@ 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 +133,16 @@ 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 diff --git a/TODO.md b/TODO.md index b8ac22ef..04f3abab 100644 --- a/TODO.md +++ b/TODO.md @@ -23,11 +23,10 @@ qemu_mode/frida_mode: - 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/docs/FAQ.md b/docs/FAQ.md index 671957ef..7869ee61 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -8,35 +8,45 @@ 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. + 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. + 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). + 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 entry point (which can be be entered by + 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). @@ -60,7 +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 @@ -75,8 +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 @@ -86,7 +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). @@ -97,15 +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 @@ -113,27 +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 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 @@ -141,7 +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 @@ -155,7 +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 c1e22e36..08d3283e 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 @@ -13,8 +14,8 @@ docker run -ti -v /location/of/your/target:/src aflplusplus/aflplusplus This image is automatically generated when a push to the stable repo happens. 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 @@ -29,10 +30,13 @@ 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 +45,25 @@ 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 @@ -67,7 +77,8 @@ 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) @@ -76,15 +87,17 @@ 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" @@ -97,20 +110,20 @@ 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 @@ -119,11 +132,13 @@ This means two things: 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 @@ -136,14 +151,16 @@ 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 @@ -151,4 +168,6 @@ 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 +[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 diff --git a/docs/afl-fuzz_approach.md b/docs/afl-fuzz_approach.md index fefde029..3804f5a0 100644 --- a/docs/afl-fuzz_approach.md +++ b/docs/afl-fuzz_approach.md @@ -445,8 +445,8 @@ 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 diff --git a/docs/best_practices.md b/docs/best_practices.md index 6a406bde..e6b252f6 100644 --- a/docs/best_practices.md +++ b/docs/best_practices.md @@ -18,7 +18,8 @@ ### 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 binary-only target @@ -27,11 +28,16 @@ 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 @@ -40,13 +46,16 @@ 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). +- 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!). +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 @@ -64,13 +73,25 @@ allows you to define network state with different type of data packets. ### 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 @@ -78,46 +99,60 @@ 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. -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) @@ -132,4 +167,5 @@ Four steps are required to do this and it also requires quite some knowledge of 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 6bee5413..2a77db82 100644 --- a/docs/custom_mutators.md +++ b/docs/custom_mutators.md @@ -4,13 +4,13 @@ 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 custom mutator. -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. +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 @@ -29,7 +29,8 @@ export AFL_CUSTOM_MUTATOR_LIBRARY="full/path/to/mutator_first.so;full/path/to/mu 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). +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. @@ -103,7 +104,8 @@ 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): @@ -121,18 +123,17 @@ def deinit(): # optional for Python - `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): @@ -144,21 +145,21 @@ 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): @@ -170,8 +171,8 @@ 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 @@ -179,8 +180,8 @@ 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 @@ -213,10 +214,10 @@ trimmed input. Here's a quick API description: - `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 built-in default trimming routine. @@ -227,10 +228,10 @@ 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` @@ -270,9 +271,10 @@ 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 first +`post_process` function of `example_first.so` will be called and then that of +`example_second.so`. ### Run @@ -300,4 +302,4 @@ 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 771bf157..3f7bdadb 100644 --- a/docs/env_variables.md +++ b/docs/env_variables.md @@ -590,79 +590,81 @@ the preferred way to configure FRIDA mode is through its * `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. + 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`. + 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 [here](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 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. + 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/fuzzing_binary-only_targets.md b/docs/fuzzing_binary-only_targets.md index a786fd8b..b3d9ca02 100644 --- a/docs/fuzzing_binary-only_targets.md +++ b/docs/fuzzing_binary-only_targets.md @@ -84,7 +84,8 @@ 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 @@ -169,7 +170,8 @@ 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 then the solutions +native to AFL++ but don't always work. ### ZAFL ZAFL is a static rewriting platform supporting x86-64 C/C++, diff --git a/docs/fuzzing_in_depth.md b/docs/fuzzing_in_depth.md index d408aa91..9611d6b7 100644 --- a/docs/fuzzing_in_depth.md +++ b/docs/fuzzing_in_depth.md @@ -259,6 +259,7 @@ Then build the target. (Usually with `make`) #### 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 @@ -307,8 +309,8 @@ 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: @@ -358,8 +360,11 @@ 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. @@ -420,22 +425,25 @@ 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! -Run it like `screen -dmS afl-main -- afl-fuzz -M main-$HOSTNAME -i ...` -and it will start away in a screen session. To enter this session, type -`screen -r afl-main`. You see - it makes sense to name the screen session -same as the afl-fuzz -M/-S naming :-) -For more information on screen or tmux, check their documentation. +the connection fails in between. Only do that though once you have verified that +your fuzzing setup works! Run it like `screen -dmS afl-main -- afl-fuzz -M +main-$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 @@ -457,12 +465,13 @@ 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++, 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). @@ -528,8 +537,8 @@ All other secondaries should be used like this: 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 @@ -553,11 +562,10 @@ recommended! ### d) Using multiple machines for fuzzing -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-$HOSTNAME`. +Maybe you have more than one machine you want to fuzz the same target on. Start +the `afl-fuzz` (and perhaps libfuzzer, honggfuzz, ...) orchestra as you like, +just ensure that your have one and only one `-M` instance per server, and that +its name is unique, hence the recommendation for `-M main-$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 diff --git a/docs/ideas.md b/docs/ideas.md index 8193983b..1a578313 100644 --- a/docs/ideas.md +++ b/docs/ideas.md @@ -1,31 +1,29 @@ # 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 @@ -34,25 +32,26 @@ Mentor: any Other programming languages also use llvm hence they could (easily?) supported 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 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. 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 82de054f..9d4523e8 100644 --- a/docs/important_changes.md +++ b/docs/important_changes.md @@ -1,6 +1,7 @@ # Important changes in AFL++ -This document lists important changes in AFL++, for example, major behavior changes. +This document lists important changes in AFL++, for example, major behavior +changes. ## From version 3.00 onwards @@ -10,8 +11,8 @@ iOS etc. 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 behaviors: * afl-fuzz: deterministic fuzzing it not a default for -M main anymore @@ -31,22 +32,22 @@ behaviors and defaults: * 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. + 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 + * 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 + * 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 environment variable `AFL_TESTCACHE_SIZE` (in MB). Good values are between 50-500 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/Scripting.md b/frida_mode/Scripting.md index fd4282db..63ab1718 100644 --- a/frida_mode/Scripting.md +++ b/frida_mode/Scripting.md @@ -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; } /* 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. |