egurra is a fuzzing tool written in Python that allows you to perform file format fuzzing. It uses a mutation based algorithm in a 'dumb' fashion. In each iteration a random file is chosen from the examples\ directory and then gets mutated by randomly replacing random amount of bytes with random values. Then, the newly mutated serves as input to an instance of the application being fuzzed which is executed in a debugged environment to monitor for possible crashes.

egurra sits upon the PyDbg Python debugger which takes care of the monitoring process. Currently only win32 environments are supported. For each crash the debugger catches, a log file with some processor state information is saved alongside the mutated input file that generated the crash for later analysis.