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Diffstat (limited to 'README.md')
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1 files changed, 37 insertions, 18 deletions
diff --git a/README.md b/README.md index 91f28118..c0a22e54 100644 --- a/README.md +++ b/README.md @@ -25,12 +25,17 @@ For comparisons use the fuzzbench `aflplusplus` setup, or use `afl-clang-fast` with `AFL_LLVM_CMPLOG=1`. -## Major changes in afl++ 3.00 onwards: +## Major behaviour changes in afl++ 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, iOS etc. +With afl++ 3.14 we introduced the following changes from previous behaviours: + * 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) + With afl++ 3.10 we introduced the following changes from previous behaviours: * 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 @@ -38,7 +43,6 @@ With afl++ 3.10 we introduced the following changes from previous behaviours: With afl++ 3.00 we introduced changes that break some previous afl and afl++ behaviours 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. @@ -572,8 +576,15 @@ 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). afl-fuzz has a variety of options that help to workaround target quirks like -specific locations for the input file (`-f`), not performing deterministic -fuzzing (`-d`) and many more. Check out `afl-fuzz -h`. +specific locations for the input file (`-f`), performing deterministic +fuzzing (`-D`) and many more. Check out `afl-fuzz -h`. + +We highly recommend that you set a memory limit for running the target with `-m` +which defines the maximum memory in MB. This prevents a potential +out-of-memory problem for your system plus helps you detect missing `malloc()` +failure 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 quadrouple 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 @@ -614,23 +625,28 @@ For every secondary fuzzer there should be a variation, e.g.: * one to three fuzzers should fuzz a target compiled with laf-intel/COMPCOV (see above). Important note: If you run more than one laf-intel/COMPCOV fuzzer and you want them to share their intermediate results, the main - fuzzer (`-M`) must be one of the them! + fuzzer (`-M`) must be one of the them! (Although this is not really + recommended.) All other secondaries should be used like this: - * A third to a half with the MOpt mutator enabled: `-L 0` - * run with a different power schedule, available are: - `fast (default), explore, coe, lin, quad, exploit, mmopt, rare, seek` - which you can set with e.g. `-p seek` + * 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` + * a few instances should use the old queue cycling with `-Z` Also it is recommended to set `export AFL_IMPORT_FIRST=1` to load testcases 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`. + 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 `-S` name. Examples are: * [Eclipser](https://github.com/SoftSec-KAIST/Eclipser/) - * [Untracer](https://github.com/FoRTE-Research/UnTracer-AFL) + * [symcc](https://github.com/eurecom-s/symcc/) * [AFLsmart](https://github.com/aflsmart/aflsmart) * [FairFuzz](https://github.com/carolemieux/afl-rb) * [Neuzz](https://github.com/Dongdongshe/neuzz) @@ -638,9 +654,11 @@ Examples are: A long list can be found at [https://github.com/Microsvuln/Awesome-AFL](https://github.com/Microsvuln/Awesome-AFL) -However you can also sync afl++ with honggfuzz, libfuzzer with -entropic, etc. +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 honggfuzz (with `-n 1` or `-n 2`) and libfuzzer in parallel is highly +recommended! #### c) The status of the fuzz campaign @@ -767,25 +785,26 @@ campaigns as these are much shorter runnings. corpus needs to be loaded. * `AFL_CMPLOG_ONLY_NEW` - only perform cmplog on new found paths, not the initial corpus as this very likely has been done for them already. - * Keep the generated corpus, use afl-cmin and reuse it everytime! + * Keep the generated corpus, use afl-cmin and reuse it every time! 2. Additionally randomize the afl++ compilation options, e.g. * 40% for `AFL_LLVM_CMPLOG` * 10% for `AFL_LLVM_LAF_ALL` 3. Also randomize the afl-fuzz runtime options, e.g. - * 60% for `AFL_DISABLE_TRIM` + * 65% for `AFL_DISABLE_TRIM` * 50% use a dictionary generated by `AFL_LLVM_DICT2FILE` - * 50% use MOpt (`-L 0`) + * 40% use MOpt (`-L 0`) * 40% for `AFL_EXPAND_HAVOC_NOW` - * 30% for old queue processing (`-Z`) + * 20% for old queue processing (`-Z`) * for CMPLOG targets, 60% for `-l 2`, 40% for `-l 3` 4. Do *not* run any `-M` modes, just running `-S` modes is better for CI fuzzing. - `-M` enables deterministic fuzzing, old queue handling etc. which is good for - a fuzzing campaign but not good for short CI runs. + `-M` enables old queue handling etc. which is good for a fuzzing campaign but + not good for short CI runs. -How this can look like can e.g. be seen at afl++'s setup in Google's [oss-fuzz](https://github.com/google/oss-fuzz/blob/4bb61df7905c6005000f5766e966e6fe30ab4559/infra/base-images/base-builder/compile_afl#L69). +How this can look like can e.g. be seen at afl++'s setup in Google's [oss-fuzz](https://github.com/google/oss-fuzz/blob/master/infra/base-images/base-builder/compile_afl) +and [clusterfuzz](https://github.com/google/clusterfuzz/blob/master/src/python/bot/fuzzers/afl/launcher.py). ## Fuzzing binary-only targets |