CS:GO map file fuzzing using AFL in QEMU mode

Author: @_niklasb

Overview article.

See LICENSE.

Prerequisites

$ sudo apt install gdb valgrind build-essential python3-minimal python-minimal
$ cd ~
$ git clone https://github.com/niklasb/gdbinit
$ cd gdbinit
$ ./setup.sh

Then, build AFL with qemu mode support and afl_patches.diff applied. Set AFL_PATH correctly in your .bashrc.

Setup

1. git clone https://github.com/niklasb/bspfuzz/ && cd bspfuzz
2. Copy over bin/ and csgo/ directories from the CS:GO server installation into the bspfuzz directory
3. Adapt offsets in main.cpp and patch.py for your version
4. ./setup.sh

Running

$ cd /path/to/bspfuzz
$ ./run_afl.sh 1
$ ./run_afl.sh 2
$ ./run_afl.sh 3
...

Triaging

$ sudo sysctl -w kernel.randomize_va_space=0
$ cd /path/to/bspfuzz/triage
$ ./triage.sh
$ ./valgrind.sh