NCC Code Navi the Text Viewer and Searcher for Code Reviewers

Released as open source by NCC Group Plc - http://www.nccgroup.com/

Developed by Ollie Whitehouse, ollie dot whitehouse at nccgroup dot com

http://www.github.com/nccgroup/dotnetpefuzzing

Released under AGPL see LICENSE for more information

Tiny .NET PE Fuzzing Harness - Proof of Concept

This code was released to support an NCC blog post. There are three basic components:

• Win.DotNetAssemblyLoad - the loader harness which watches a directory a tries to load any modules
• Win.Module - a simple managed .NET module (i.e. DLL)
• Win.NULLFuzzer - a simple fuzz which just walks through and set each byte of the input file to null

It would be run something like this:

• Compile the module
• Start the harness watching a directory
• Attach WinDbg / debugger of choice to the harness to see any interesting yet handled exceptions in unmanaged code
• Fuzz and produce DLL test cases in the directory the harness is monitoring

• Win.DotNetAssemblyLoad C:!Research\Fuzzing\DotNetPE\TestCases
• now attached WinDbg to the process
• Win.NULLFuzzer.exe C:!Research\DotNetPE\Win.Module.dll C:!Research\Fuzzing\DotNetPE\TestCases

This simple example on how to approach the problem did not find any issues in the 4.x runtime :)