Testing Handbook Skills
Skills from the Trail of Bits Application Security Testing Handbook (appsec.guide)
- Type
- Plugin
- Repository
- trailofbits/skills
- GitHub stars
- 7.3k
- License
- CC-BY-SA-4.0
- Repo last updated
- Sep 25, 2026
- Version
- 1.2.2
- Author
- Paweł Płatek
What Testing Handbook Skills is
Testing Handbook Skills is a plugin published in the trailofbits/skills repository on GitHub, which has about 7.3k stars. The repository describes itself as: “Trail of Bits Claude Code skills for security research, vulnerability detection, and audit workflows”
A plugin is a package that bundles skills, slash commands, subagents, hooks, and MCP connectors so they install together. Plugins are plain files with a manifest at .claude-plugin/plugin.json, and they work in both Claude Code and Claude Cowork.
Installing Testing Handbook Skills adds everything it ships in one step. Connectors inside a plugin still need to be connected separately, and hooks and subagents only run in Cowork and Claude Code, not in regular chat.
How to install Testing Handbook Skills
Claude Code
- Add the repository as a plugin marketplace: claude plugin marketplace add trailofbits/skills
- Install the plugin: claude plugin install testing-handbook-skills@<marketplace-name>, using the marketplace name from the repository's .claude-plugin/marketplace.json.
- Restart the session if the new skills or commands don't appear straight away.
Claude Cowork
- Open Customize → Plugins and choose Add marketplace.
- Enter trailofbits/skills (the owner/repo shorthand works for GitHub).
- Find Testing Handbook Skills in the list, click Install, then connect any connectors it needs from its Connectors tab.
New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.
Inside the source file
An excerpt from plugins/testing-handbook-skills/.claude-plugin/plugin.json, shared under the repository's CC-BY-SA-4.0 license. Read the full file on GitHub.
Meta-skill that generates Claude Code skills from the Trail of Bits Application Security Testing Handbook.
Overview
This plugin provides a skill generator that:
- Analyzes the Testing Handbook structure
- Identifies skill candidates (tools, techniques, domains)
- Generates skills using appropriate templates
- Validates generated skills
Installation
Add to your Claude Code skills configuration:
# From the skills marketplace
claude skills install testing-handbook-skills
# Or manually add to .claude/settings.json
{
"plugins": [
"./plugins/testing-handbook-skills"
]
}Usage
Generate All Skills
Generate skills from the testing handbookThis will:
- Locate the handbook (check common locations, ask user, or clone)
- Scan the handbook structure
- Present a plan of skills to generate
- On approval, generate skills as siblings to testing-handbook-generator/
Generate Specific Skill
Create a skill for the libFuzzer section of the testing handbookStructure
plugins/testing-handbook-skills/
├── .claude-plugin/
│ └── plugin.json
├── scripts/
│ └── validate-skills.py # Skill validation tool
├── skills/
│ ├── testing-handbook-generator/
│ │ ├── SKILL.md # Main skill entry point
│ │ ├── discovery.md # Handbook analysis methodology
│ │ ├── testing.md # Validation strategy
│ │ ├── agent-prompt.md # Agent prompt template for generation
│ │ └── templates/ # Skill generation templates
│ │ ├── tool-skill.md # Semgrep, CodeQL
│ │ ├── fuzzer-skill.md # libFuzzer, AFL++, cargo-fuzz
│ │ ├── technique-skill.md # Harness writing, coverage
│ │ └── domain-skill.md # Crypto testing, web security
│ ├── [generated-skill]/ # Generated skills (siblings to generator)
│ │ └── SKILL.md
…Scripts
# Validate all skills
uv run scripts/validate-skills.py
# Validate specific skill
uv run scripts/validate-skills.py --skill libfuzzer
# JSON output for CI
uv run scripts/validate-skills.py --jsonSkill Types
Generated Skills
Generated skills are written as siblings to the generator:
skills/[skill-name]/SKILL.mdEach generated skill:
- Follows the appropriate template structure
- Contains content extracted from the handbook
- Includes resource links (WebFetch summaries for non-videos)
- Is validated with scripts/validate-skills.py before delivery
Skills Cross-Reference
This graph shows the 14 generated skills and their cross-references (from the Related Skills section of each skill). Only links between actually generated skills are shown.
graph TB
subgraph Fuzzers
libfuzzer[libfuzzer]
aflpp[aflpp]
libafl[libafl]
cargo-fuzz[cargo-fuzz]
atheris[atheris]
ruzzy[ruzzy]
end
subgraph Techniques
harness-writing[harness-writing]
address-sanitizer[address-sanitizer]
coverage-analysis[coverage-analysis]
fuzzing-dictionary[fuzzing-dictionary]
fuzzing-obstacles[fuzzing-obstacles]
ossfuzz[ossfuzz]
end
…Legend:
- Solid arrows (→): Primary dependencies (techniques, tools used together)
- Dashed arrows (-.->): Alternative suggestions (similar tools/fuzzers)
Generated Skills Summary:
Note: Some skills reference planned/external skills not yet generated (e.g., honggfuzz, fuzzing-corpus, sarif-parsing). Run validate-skills.py to see the full list.
Configuration
The skill will automatically:
- Check common locations (./testing-handbook, ../testing-handbook, ~/testing-handbook)
- Ask the user for the path if not found
- Clone from GitHub as last resort: https://github.com/trailofbits/testing-handbook
No hardcoded paths are used - the skill adapts to your environment.
Author
Paweł Płatek
License
See repository license.
Before you install
- Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
- Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
- Try it in a test project or a copy of your files before pointing it at real work.
- Pin the version you tested, and review changes before updating.
- Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.
FAQ
What is Testing Handbook Skills?
Testing Handbook Skills is a plugin for Claude Code and Claude Cowork from the trailofbits/skills repository on GitHub. Skills from the Trail of Bits Application Security Testing Handbook (appsec.guide)
How do I install Testing Handbook Skills in Claude Code?
Add the repository as a plugin marketplace: claude plugin marketplace add trailofbits/skills Install the plugin: claude plugin install testing-handbook-skills@<marketplace-name>, using the marketplace name from the repository's .claude-plugin/marketplace.json. Restart the session if the new skills or commands don't appear straight away.
Can I use Testing Handbook Skills in Claude Cowork?
Open Customize → Plugins and choose Add marketplace. Enter trailofbits/skills (the owner/repo shorthand works for GitHub). Find Testing Handbook Skills in the list, click Install, then connect any connectors it needs from its Connectors tab.
Is Testing Handbook Skills safe to install?
It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.
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