Fuzzing framework written in OCaml
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OFuzz is a fuzzing platform written in OCaml. OFuzz currently focuses on file-processing applications that run on *nix platforms. The main design principle of OFuzz is flexibility: it must be easy to add/replace fuzzing components (crash triaging module, test case generator, etc.) or algorithms (mutation algorithms, scheduling algorithms).

OFuzz provides a rich set of APIs to develop new mutation algorithms, crash triaging algorithms, and also configuration scheduling algorithms. For example, implementing a new mutation algorithm is as easy as writing a single OCaml file that contains a function of a certain type thanks to OCaml's module system. Implementing a crash triaging algorithm is equivalent to implementing a single OCaml module.

We observed that previous fuzzers have their own sampling algorithms that are hard to be modeled using a closed-form expression. Thus, the motivation of OFuzz is to introduce a mutational fuzzing framework that provides mutation algorithms based on formal statistical sampling processes. The design of OFuzz should enable security researchers to design their own algorithms, and test them. Our goal is to encourage formal study in fuzzing.

Currently, OFuzz supports four different bit-flipping mutation algorithms. OFuzz supports not only mathematical algorithms, but also one of the practical fuzzing algorithms derived from zzuf (http://caca.zoy.org/wiki/zzuf), which essentially divides an input seed into multiple chunks and applies bit-flipping algorithm for each chunk. See Mutation Algorithms for more details about the mutation algorithms of OFuzz.


Make sure you installed the following dependencies for compilation.

  • With OPAM (Linux & Mac OS X)

    We recommend using OPAM (http://opam.ocamlpro.com/).

    opam install ocamlfind yojson camlidl mysql camlbz2 batteries curses
  • Without OPAM (Debian, Ubuntu)

    If you prefer not to use OPAM, you can also use OS-specific packages. For example, in Debian:

    sudo apt-get install build-essential \
         ocaml libfindlib-ocaml-dev camlidl \
         libgmp-dev libmpfr-dev libmpc-dev \
         libboost-dev libboost-filesystem-dev \
         libbatteries-ocaml-dev libyojson-ocaml-dev \
         libmysql-ocaml-dev libbz2-ocaml-dev libncurses5-dev

Once you have installed all the necessary packages, simply run:


To run OFuzz, one needs the followings.

  • GDB (with Python support: must be compiled with --with-python) or LLDB
  • Xvfb (optional, for fuzzing GUI applications remotely)
  • X11vnc (option, for fuzzing GUI applications remotely)

Intalling OFuzz from a binary distribution

A binary distribution requires several libraries to run properly.

  • Debian / Ubuntu

    sudo apt-get install -y --force-yes \
         libboost-filesystem1.49.0 libmysqlclient18 xvfb x11vnc gdb screen

Running OFuzz

Suppose we are fuzzing a program FFMpeg with a seed file called "seed.mp4". We can run OFuzz in two steps as follows. See the wiki page for more usage help.

  1. Create an OFuzz configuration file (ffmpeg.conf) as follows. Please refer to our wiki page for further information about OFuzz configuration file.
    "cmds" : ["/usr/bin/ffmpeg", "-i", "SEED.mp4", "foo.avi"],
    "filearg" : 2,
    "mratiostart" : 0.001,
    "seedfile" : "/path/to/seed.mp4"

A conf file needs to contain at least four entries: (1) cmds specifies the command line arguments for executing FFmpeg; (2) filearg specifies which argument in the cmds is the seed file. If it is 2, that means the 3rd argument is the seed; (3) mratiostart specifies a mutation ratio for mutating the seed; (4) seedfile is a path to the seed file.

  1. Run OFuzz!
./ofuzz ./ffmpeg.conf

See the wiki page for more usage help.

Release Notes

See Release Notes.