Ruzzy
Sets up and runs Ruzzy, Trail of Bits' coverage-guided Ruby fuzzer and the only...
Install
npx skills add trailofbits/skills --skill ruzzy -g -a claude-code -y- Repository
- trailofbits/skills7.9k
- Category
- Testing
- Updated
- 7d ago
- License
- CC-BY-SA-4.0
- Context cost
- Mediumabout 2,943 tokens
- Runs scripts
- No, instructions only
What it does
Sets up and runs Ruzzy, Trail of Bits' coverage-guided Ruby fuzzer and the only production-ready one for the language. Covers harness structure, fuzzing pure Ruby and the native C extensions in gems, and sanitizer builds. Use when fuzzing a Ruby library or gem, testing a Ruby C extension for memory safety, or asking how to fuzz Ruby at all.
Ruzzy
Ruzzy is a coverage-guided fuzzer for Ruby built on libFuzzer. It enables fuzzing both pure Ruby code and Ruby C extensions with sanitizer support for detecting memory corruption and undefined behavior.
When to Use
Ruzzy is currently the only production-ready coverage-guided fuzzer for Ruby.
Choose Ruzzy when:
- Fuzzing Ruby applications or libraries
- Testing Ruby C extensions for memory safety issues
- You need coverage-guided fuzzing for Ruby code
- Working with Ruby gems that have native extensions
Quick Start
Set up environment:
export ASAN_OPTIONS="allocator_may_return_null=1:detect_leaks=0:use_sigaltstack=0"
Test with the included toy example:
LD_PRELOAD=$(ruby -e 'require "ruzzy"; print Ruzzy::ASAN_PATH') \
ruby -e 'require "ruzzy"; Ruzzy.dummy'
This should quickly find a crash demonstrating that Ruzzy is working correctly.
Installation
Platform Support
Ruzzy supports Linux x86-64 and AArch64/ARM64. For macOS or Windows, use the Dockerfile or development environment.
Prerequisites
- Linux x86-64 or AArch64/ARM64
- Recent version of clang (tested back to 14.0.0, latest release recommended)
- Ruby with gem installed
Installation Command
Install Ruzzy with clang compiler flags:
MAKE="make --environment-overrides V=1" \
CC="/path/to/clang" \
CXX="/path/to/clang++" \
LDSHARED="/path/to/clang -shared" \
LDSHAREDXX="/path/to/clang++ -shared" \
gem install ruzzy
Environment variables explained:
MAKE: Overrides make to respect subsequent environment variablesCC,CXX,LDSHARED,LDSHAREDXX: Ensure proper clang binaries are used for latest features
Troubleshooting Installation
If installation fails, enable debug output:
RUZZY_DEBUG=1 gem install --verbose ruzzy
