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FuzzDiff tool


I'd like to announce FuzzDiff, a simple tool to help make crash
analysis during file format fuzzing a bit easier.  I'm sure many
people have written similar tools for their own purposes, but I
haven't seen any that are publicly available.  Hopefully at least one
person finds it useful.

When provided with a fuzzed file, a corresponding original un-fuzzed
file, and the path to the targeted program, FuzzDiff will selectively
"un-fuzz" portions of the fuzzed file while re-launching the
application to monitor for crashes.  This will yield a file that still
crashes the target application, but contains a minimum set of changes
from the original, un-fuzzed file.  This can be useful in pinning down
the exact cause of a crash.

The tool is written in Python and currently only works on Unix-based
systems, since it monitors for crashes by checking for SIGSEGV.  It
also assumes that the target program adheres to the syntax "[program]
[args] [input file]".  Both of these limitations can be easily worked
around.  The code is hardly what I'd call production-ready, but it
gets the job done.

The tool is available at:

Happy hacking,
Dan Rosenberg