# Testing Handbook Skills > Trail of Bits' skills for fuzzing and crypto testing, from its Testing Handbook: libFuzzer, AFL++, cargo-fuzz, Atheris, OSS-Fuzz and more. Testing Handbook Skills is Trail of Bits' set of Agent Skills built from its Application Security Testing Handbook (appsec.guide). They teach your agent how to set up and run fuzzers, write harnesses that find real bugs, read sanitizer and coverage output, and test cryptographic code against known attacks and timing leaks. What its skills teach your agent - Fuzzers: libFuzzer and AFL++ for C and C++, cargo-fuzz for Rust, LibAFL for building custom fuzzers, Atheris for Python and its C extensions, and Ruzzy, Trail of Bits' fuzzer for Ruby and native gems - Harness writing: map raw bytes onto the API you're testing, generate structured inputs, and avoid non-determinism and crashes that won't reproduce - Getting a campaign to work: AddressSanitizer builds and crash reports, coverage analysis, fuzzing dictionaries, and patching past checksums, magic values and other checks that stall a fuzzer - Continuous fuzzing: enroll an open-source project in OSS-Fuzz, test its build locally and reproduce its crash reports - Crypto testing: check an implementation against Project Wycheproof's test vectors, and measure timing side channels with dudect and Timecop - A generator skill that writes new skills from the handbook's sections and checks them with its validator How it connects - In Claude Code, run /plugin marketplace add trailofbits/skills, then install testing-handbook-skills from /plugin menu. In Codex, run codex plugin marketplace add trailofbits/skills, then codex plugin add testing-handbook-skills@trailofbits. - The skills are plain Agent Skills, so other agents that read skills can use them too. - There's no account or sign-in. The fuzzers and compilers run on your machine, and the skills tell your agent how to install and drive them. Good to know - These skills are guidance for your agent, not a scanner: your agent writes the harnesses and runs the tools in your project. - Trail of Bits' marketplace has many other security plugins, from static analysis to supply-chain audits, each installed on its own. - Type: Skill - Made by: trailofbits - Category: Security - Formats: Skills, Claude plugins - Version: latest - Website: https://appsec.guide - Source: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills - Page: https://pluginboard.ai/skills/testing-handbook-skills ## Works with - ChatGPT - Claude - Gemini - GitHub Copilot - Cursor - Claude Code - Codex - Antigravity - Gemini CLI - Replit - OpenClaw - OpenCode - Hermes Agent ## Install ### ChatGPT In ChatGPT: Download the testing-handbook-skills folder and zip it, then Plugins → Skills → Create → Upload from your computer. Business and Enterprise plans. View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### Claude In Claude (web or desktop): Download each skill’s folder and zip it, then upload them one at a time in Customize → Skills. View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### Gemini In Gemini: Download the testing-handbook-skills folder, then at gemini.google.com click Customize → Skills → Create → Upload and pick the folder (or a .zip of it). View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### GitHub Copilot Copy all 15 skills, in your terminal: ```shell npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/address-sanitizer ~/.copilot/skills/address-sanitizer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/aflpp ~/.copilot/skills/aflpp npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/atheris ~/.copilot/skills/atheris npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/cargo-fuzz ~/.copilot/skills/cargo-fuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/constant-time-testing ~/.copilot/skills/constant-time-testing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/coverage-analysis ~/.copilot/skills/coverage-analysis npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-dictionary ~/.copilot/skills/fuzzing-dictionary npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-obstacles ~/.copilot/skills/fuzzing-obstacles npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/harness-writing ~/.copilot/skills/harness-writing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libafl ~/.copilot/skills/libafl npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.copilot/skills/libfuzzer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ossfuzz ~/.copilot/skills/ossfuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ruzzy ~/.copilot/skills/ruzzy npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/testing-handbook-generator ~/.copilot/skills/testing-handbook-generator npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/wycheproof ~/.copilot/skills/wycheproof ``` View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### Cursor Copy all 15 skills, in your terminal: ```shell npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/address-sanitizer ~/.cursor/skills/address-sanitizer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/aflpp ~/.cursor/skills/aflpp npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/atheris ~/.cursor/skills/atheris npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/cargo-fuzz ~/.cursor/skills/cargo-fuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/constant-time-testing ~/.cursor/skills/constant-time-testing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/coverage-analysis ~/.cursor/skills/coverage-analysis npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-dictionary ~/.cursor/skills/fuzzing-dictionary npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-obstacles ~/.cursor/skills/fuzzing-obstacles npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/harness-writing ~/.cursor/skills/harness-writing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libafl ~/.cursor/skills/libafl npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.cursor/skills/libfuzzer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ossfuzz ~/.cursor/skills/ossfuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ruzzy ~/.cursor/skills/ruzzy npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/testing-handbook-generator ~/.cursor/skills/testing-handbook-generator npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/wycheproof ~/.cursor/skills/wycheproof ``` View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### Claude Code In Claude Code, as a plugin: ```text /plugin marketplace add trailofbits/skills /plugin install testing-handbook-skills@trailofbits ``` Copy all 15 skills, in your terminal: ```shell npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/address-sanitizer ~/.claude/skills/address-sanitizer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/aflpp ~/.claude/skills/aflpp npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/atheris ~/.claude/skills/atheris npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/cargo-fuzz ~/.claude/skills/cargo-fuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/constant-time-testing ~/.claude/skills/constant-time-testing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/coverage-analysis ~/.claude/skills/coverage-analysis npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-dictionary ~/.claude/skills/fuzzing-dictionary npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-obstacles ~/.claude/skills/fuzzing-obstacles npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/harness-writing ~/.claude/skills/harness-writing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libafl ~/.claude/skills/libafl npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.claude/skills/libfuzzer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ossfuzz ~/.claude/skills/ossfuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ruzzy ~/.claude/skills/ruzzy npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/testing-handbook-generator ~/.claude/skills/testing-handbook-generator npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/wycheproof ~/.claude/skills/wycheproof ``` View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### Codex Copy all 15 skills, in your terminal: ```shell npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/address-sanitizer ~/.agents/skills/address-sanitizer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/aflpp ~/.agents/skills/aflpp npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/atheris ~/.agents/skills/atheris npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/cargo-fuzz ~/.agents/skills/cargo-fuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/constant-time-testing ~/.agents/skills/constant-time-testing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/coverage-analysis ~/.agents/skills/coverage-analysis npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-dictionary ~/.agents/skills/fuzzing-dictionary npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-obstacles ~/.agents/skills/fuzzing-obstacles npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/harness-writing ~/.agents/skills/harness-writing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libafl ~/.agents/skills/libafl npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.agents/skills/libfuzzer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ossfuzz ~/.agents/skills/ossfuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ruzzy ~/.agents/skills/ruzzy npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/testing-handbook-generator ~/.agents/skills/testing-handbook-generator npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/wycheproof ~/.agents/skills/wycheproof ``` View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### Antigravity In Antigravity: Copy the testing-handbook-skills folder into ~/.gemini/config/skills (Antigravity app and IDE) or ~/.gemini/antigravity-cli/skills (Antigravity CLI). View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### Gemini CLI Copy all 15 skills, in your terminal: ```shell npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/address-sanitizer ~/.gemini/skills/address-sanitizer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/aflpp ~/.gemini/skills/aflpp npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/atheris ~/.gemini/skills/atheris npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/cargo-fuzz ~/.gemini/skills/cargo-fuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/constant-time-testing ~/.gemini/skills/constant-time-testing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/coverage-analysis ~/.gemini/skills/coverage-analysis npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-dictionary ~/.gemini/skills/fuzzing-dictionary npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-obstacles ~/.gemini/skills/fuzzing-obstacles npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/harness-writing ~/.gemini/skills/harness-writing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libafl ~/.gemini/skills/libafl npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.gemini/skills/libfuzzer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ossfuzz ~/.gemini/skills/ossfuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ruzzy ~/.gemini/skills/ruzzy npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/testing-handbook-generator ~/.gemini/skills/testing-handbook-generator npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/wycheproof ~/.gemini/skills/wycheproof ``` View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### Replit Copy all 15 skills, in your terminal: ```shell npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/address-sanitizer .agents/skills/address-sanitizer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/aflpp .agents/skills/aflpp npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/atheris .agents/skills/atheris npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/cargo-fuzz .agents/skills/cargo-fuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/constant-time-testing .agents/skills/constant-time-testing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/coverage-analysis .agents/skills/coverage-analysis npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-dictionary .agents/skills/fuzzing-dictionary npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-obstacles .agents/skills/fuzzing-obstacles npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/harness-writing .agents/skills/harness-writing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libafl .agents/skills/libafl npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer .agents/skills/libfuzzer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ossfuzz .agents/skills/ossfuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ruzzy .agents/skills/ruzzy npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/testing-handbook-generator .agents/skills/testing-handbook-generator npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/wycheproof .agents/skills/wycheproof ``` View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### OpenClaw Copy all 15 skills, in your terminal: ```shell npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/address-sanitizer ~/.openclaw/skills/address-sanitizer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/aflpp ~/.openclaw/skills/aflpp npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/atheris ~/.openclaw/skills/atheris npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/cargo-fuzz ~/.openclaw/skills/cargo-fuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/constant-time-testing ~/.openclaw/skills/constant-time-testing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/coverage-analysis ~/.openclaw/skills/coverage-analysis npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-dictionary ~/.openclaw/skills/fuzzing-dictionary npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-obstacles ~/.openclaw/skills/fuzzing-obstacles npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/harness-writing ~/.openclaw/skills/harness-writing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libafl ~/.openclaw/skills/libafl npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.openclaw/skills/libfuzzer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ossfuzz ~/.openclaw/skills/ossfuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ruzzy ~/.openclaw/skills/ruzzy npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/testing-handbook-generator ~/.openclaw/skills/testing-handbook-generator npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/wycheproof ~/.openclaw/skills/wycheproof ``` View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### OpenCode Copy all 15 skills, in your terminal: ```shell npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/address-sanitizer ~/.config/opencode/skills/address-sanitizer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/aflpp ~/.config/opencode/skills/aflpp npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/atheris ~/.config/opencode/skills/atheris npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/cargo-fuzz ~/.config/opencode/skills/cargo-fuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/constant-time-testing ~/.config/opencode/skills/constant-time-testing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/coverage-analysis ~/.config/opencode/skills/coverage-analysis npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-dictionary ~/.config/opencode/skills/fuzzing-dictionary npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-obstacles ~/.config/opencode/skills/fuzzing-obstacles npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/harness-writing ~/.config/opencode/skills/harness-writing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libafl ~/.config/opencode/skills/libafl npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.config/opencode/skills/libfuzzer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ossfuzz ~/.config/opencode/skills/ossfuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ruzzy ~/.config/opencode/skills/ruzzy npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/testing-handbook-generator ~/.config/opencode/skills/testing-handbook-generator npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/wycheproof ~/.config/opencode/skills/wycheproof ``` View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills ### Hermes Agent Copy all 15 skills, in your terminal: ```shell npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/address-sanitizer ~/.hermes/skills/address-sanitizer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/aflpp ~/.hermes/skills/aflpp npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/atheris ~/.hermes/skills/atheris npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/cargo-fuzz ~/.hermes/skills/cargo-fuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/constant-time-testing ~/.hermes/skills/constant-time-testing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/coverage-analysis ~/.hermes/skills/coverage-analysis npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-dictionary ~/.hermes/skills/fuzzing-dictionary npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/fuzzing-obstacles ~/.hermes/skills/fuzzing-obstacles npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/harness-writing ~/.hermes/skills/harness-writing npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libafl ~/.hermes/skills/libafl npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/libfuzzer ~/.hermes/skills/libfuzzer npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ossfuzz ~/.hermes/skills/ossfuzz npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/ruzzy ~/.hermes/skills/ruzzy npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/testing-handbook-generator ~/.hermes/skills/testing-handbook-generator npx -y degit trailofbits/skills/plugins/testing-handbook-skills/skills/wycheproof ~/.hermes/skills/wycheproof ``` View the skills on GitHub: https://github.com/trailofbits/skills/tree/HEAD/plugins/testing-handbook-skills --- From Pluginboard (https://pluginboard.ai).