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Diffstat (limited to 'docs/fuzzing_in_depth.md')
| -rw-r--r-- | docs/fuzzing_in_depth.md | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/docs/fuzzing_in_depth.md b/docs/fuzzing_in_depth.md index 92c9910b..f75ca5dc 100644 --- a/docs/fuzzing_in_depth.md +++ b/docs/fuzzing_in_depth.md @@ -523,7 +523,7 @@ mode!) and switch the input directory with a dash (`-`): afl-fuzz -i - -o output -- bin/target -someopt @@ ``` -Adding a dictionary is helpful. You have to following options: +Adding a dictionary is helpful. You have the following options: * See the directory [dictionaries/](../dictionaries/), if something is already included for your @@ -534,6 +534,8 @@ dictionaries/FORMAT.dict`. * With `afl-clang-fast`, you can set `AFL_LLVM_DICT2FILE=/full/path/to/new/file.dic` to automatically generate a dictionary during target compilation. + Adding `AFL_LLVM_DICT2FILE_NO_MAIN=1` to not parse main (usually command line + parameter parsing) is often a good idea too. * You also have the option to generate a dictionary yourself during an independent run of the target, see [utils/libtokencap/README.md](../utils/libtokencap/README.md). @@ -628,7 +630,8 @@ 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 the queue in the CI is huge and/or the execution time is slow then you can also add `AFL_NO_STARTUP_CALIBRATION=1` to skip the initial queue calibration -phase and start fuzzing at once. +phase and start fuzzing at once - but only do this if the calibration phase +would be too long for your fuzz run time. 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 @@ -672,7 +675,7 @@ The syncing process itself is very simple. As the `-M main-$HOSTNAME` instance syncs to all `-S` secondaries as well as to other fuzzers, you have to copy only this directory to the other machines. -Lets say all servers have the `-o out` directory in /target/foo/out, and you +Let's say all servers have the `-o out` directory in /target/foo/out, and you created a file `servers.txt` which contains the hostnames of all participating servers, plus you have an ssh key deployed to all of them, then run: @@ -900,6 +903,13 @@ 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. +`casr-afl` from [CASR](https://github.com/ispras/casr) tools provides +comfortable triaging for crashes found by AFL++. Reports are clustered and +contain severity and other information. +```shell +casr-afl -i /path/to/afl/out/dir -o /path/to/casr/out/dir +``` + ## 5. CI fuzzing Some notes on continuous integration (CI) fuzzing - this fuzzing is different to @@ -907,7 +917,8 @@ normal fuzzing campaigns as these are much shorter runnings. If the queue in the CI is huge and/or the execution time is slow then you can also add `AFL_NO_STARTUP_CALIBRATION=1` to skip the initial queue calibration -phase and start fuzzing at once. +phase and start fuzzing at once. But only do that if the calibration time is +too long for your overall available fuzz run time. 1. Always: * LTO has a much longer compile time which is diametrical to short fuzzing - @@ -928,7 +939,7 @@ phase and start fuzzing at once. 3. Also randomize the afl-fuzz runtime options, e.g.: * 65% for `AFL_DISABLE_TRIM` * 50% for `AFL_KEEP_TIMEOUTS` - * 50% use a dictionary generated by `AFL_LLVM_DICT2FILE` + * 50% use a dictionary generated by `AFL_LLVM_DICT2FILE` + `AFL_LLVM_DICT2FILE_NO_MAIN=1` * 40% use MOpt (`-L 0`) * 40% for `AFL_EXPAND_HAVOC_NOW` * 20% for old queue processing (`-Z`) |