Trail of Bits

Grammar-based mutation

Umberto

Structured-data mutator for JSON, XML, X.509, and other grammar-shaped inputs.

View on GitHub trailofbits/umberto

Best for

Fuzzing scenarios where preserving structure is more valuable than raw noise.

Surface

Grammar-based mutation

Catalog group

Model strange files, parsers, and data flow

Repository

trailofbits/umberto

From the README

Umberto is a library designed for mutating generic structured data (e.g., JSON, XML, X.509) and a command line application wrapping this functionality. It can apply a variety of mutations, synthesize totally new values, and apply existing mutators (e.g. Radamsa) to structure components. If you're trying to perform grammar-based fuzzing, you might find it very useful.
Read the full README on GitHub ↗

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