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WinAFL-TinyInst

What is WinAFL-TinyInst

Added TinyInst to afl-fuzz.c with option -Z.

Building WinAFL-TinyInst

  1. If you are building with DynamoRIO support, download and build DynamoRIO sources or download DynamoRIO Windows binary package from https://github.com/DynamoRIO/dynamorio/releases

  2. Pull third party dependencies by running git submodule update --init --recursive from the WinAFL-TinyInst source directory

  3. Edit TinyInst/Windows/debugger.cpp

    -   sinkhole_stds = false;
+   sinkhole_stds = true;

  4. Open Visual Studio Command Prompt (or Visual Studio x64 Win64 Command Prompt if you want a 64-bit build). Note that you need a 64-bit winafl.dll build if you are fuzzing 64-bit targets and vice versa.

  5. Go to the directory containing the source

  6. Type the following commands. Modify the -DDynamoRIO_DIR flag to point to the location of your DynamoRIO cmake files (either full path or relative to the source directory).

For a 32-bit build:

mkdir build32
cd build32
cmake -G"Visual Studio 16 2019" -A Win32 .. -DDynamoRIO_DIR=..\path\to\DynamoRIO\cmake -DINTELPT=1
cmake --build . --config Release

For a 64-bit build:

mkdir build64
cd build64
cmake -G"Visual Studio 16 2019" -A x64 .. -DDynamoRIO_DIR=..\path\to\DynamoRIO\cmake -DINTELPT=1
cmake --build . --config Release

Build configuration options

The following cmake configuration options are supported:

  • -DDynamoRIO_DIR=..\path\to\DynamoRIO\cmake - Needed to build the winafl.dll DynamoRIO client

  • -DINTELPT=1 - Enable Intel PT mode. For more information see https://github.com/googleprojectzero/winafl/blob/master/readme_pt.md

  • -DUSE_COLOR=1 - color support (Windows 10 Anniversary edition or higher)

  • -DUSE_DRSYMS=1 - Drsyms support (use symbols when available to obtain -target_offset from -target_method). Enabling this has been known to cause issues on Windows 10 v1809, though there are workarounds, see googleprojectzero/winafl#145

Using WinAFL-TinyInst

The command line for afl-fuzz on Windows is different than on Linux. Instead of:

%s [ afl options ] -- target_cmd_line

it now looks like this:

afl-fuzz [afl options] -- [instrumentation options] -- target_cmd_line

The following afl-fuzz options are supported:

  -i dir        - input directory with test cases
  -o dir        - output directory for fuzzer findings
  -t msec       - timeout for each run
  -s            - deliver sample via shared memory
  -D dir        - directory containing DynamoRIO binaries (drrun, drconfig)
  -w path       - path to winafl.dll
  -e            - expert mode to run WinAFL-TinyInst as a DynamoRIO tool
  -P            - use Intel PT tracing mode
  -Y            - enable the static instrumentation mode
  -Z            - use TinyInst
  -f file       - location read by the fuzzed program
  -m limit      - memory limit for the target process
  -p            - persist DynamoRIO cache across target process restarts
  -c cpu        - the CPU to run the fuzzed program
  -d            - quick & dirty mode (skips deterministic steps)
  -n            - fuzz without instrumentation (dumb mode)
  -x dir        - optional fuzzer dictionary
  -I msec       - timeout for process initialization and first run
  -T text       - text banner to show on the screen
  -M \\ -S id   - distributed mode
  -C            - crash exploration mode (the peruvian rabbit thing)
  -l path       - a path to user-defined DLL for custom test cases processing
  -A module     - a module identifying a unique process to attach to

Example:

afl-fuzz.exe -Z -i in -o out -M test_1 -p fast -t 10000+ -- -callconv fastcall -target_method main -nargs 2 -loop -persist -iterations 5000 -instrument_module gdiplus.dll -instrument_module WindowsCodecs.dll -target_module test_gdiplus.exe -- test_gdiplus.exe @@

References