Custom mutators enhance and alter the mutation strategies of afl++. For further information and documentation on how to write your own, read the docs.
If you use git to clone afl++, then the following will incorporate our excellent grammar custom mutator:
git submodule update --initRead the README in the Grammar-Mutator repository on how to use it.
This directory holds ready to use custom mutators. Just type "make" in the individual subdirectories.
Use with e.g.
AFL_CUSTOM_MUTATOR_LIBRARY=custom_mutators/radamsa/radamsa-mutator.so afl-fuzz ....
and add AFL_CUSTOM_MUTATOR_ONLY=1 if you only want to use the custom mutator.
Multiple custom mutators can be used by separating their paths with : in the environment variable.
Adrian Tiron ported the Superion grammar fuzzer to afl++, it is WIP and requires cmake (among other things): https://github.com/adrian-rt/superion-mutator
There are two WIP protobuf projects, that require work to be working though:
transforms protobuf raw: https://github.com/bruce30262/libprotobuf-mutator_fuzzing_learning/tree/master/4_libprotobuf_aflpp_custom_mutator
has a transform function you need to fill for your protobuf format, however needs to be ported to the updated afl++ custom mutator API (not much work): https://github.com/thebabush/afl-libprotobuf-mutator