AFL Targets

To fuzz targets written for AFL, replace calls to AFL's compilers (i.e. afl-clang,afl-clang++ etc) with FUZZ_STANDALONE_CC and FUZZ_STANDALONE_CXX. If you have a configurable build system, this may look something like:


Ensure that you also use the CFLAGS and CXXFLAGS provided in the build environment. You can append your own, but be sure to include the Fuzzbuzz-provided ones. These help us build special versions of your target to track metrics like code coverage.

Then, in the harness field, specify whether the binary takes input via stdin, or from a file. If the binary takes input from a file, mark the location in the binary's command line where the input file should be placed with a @@. This will be replaced automatically when fuzzing.

AFL configuration options like memory limit, timeout threshold and dictionary can also be set in the configuration file. This is an example of a configuration file with all the features described above:

language: c++
- name: my-target
# you can specify your own CFLAGS/CXXFLAGS, just remember to
# use the fuzzbuzz-provided defaults as well
- $FUZZ_STANDALONE_CXX $CXXFLAGS my_binary.cpp -o ./target
corpus: ./my_target/corpus
timeout: 500 # in milliseconds
memory_limit: 1000 # in megabytes
dictionary: ./my_target/dict # location of dictionary file
binary: ./target @@
# input can be one of: stdin, file, socket
input: file

You're ready to go! Push your project to Fuzzbuzz and it will detect your targets automatically.

Check out our Advanced Configuration documentation to learn how to use sanitizers on Fuzzbuzz