Testing Handbook Skills

Comprehensive security testing toolkit generated from the Trail of Bits Application Security Testing Handbook.

When to Use

• Setting up fuzzing campaigns for C/C++, Rust, Python, or Ruby
• Writing fuzzing harnesses for target functions
• Analyzing code coverage to guide testing
• Running sanitizers (AddressSanitizer, UBSan, MSan) to catch memory bugs
• Performing constant-time testing for cryptographic code
• Using Wycheproof test vectors for crypto validation

When NOT to Use

• Smart contract auditing (use security-building-secure-contracts)
• Writing custom Semgrep rules (use semgrep-rule-creator)
• General code review (use security-differential-review)
• Vulnerability hunting without a testing plan (use audit-context-building first)

Sub-Skills (17 total)

Fuzzers

Fuzzer	Language	Best For	Skill Path
libFuzzer	C/C++	LLVM-based coverage-guided fuzzing	skills/libfuzzer/SKILL.md
AFL++	C/C++	Advanced mutation-based fuzzing	skills/aflpp/SKILL.md
libAFL	C/C++	LibAFL-based custom fuzzers	skills/libafl/SKILL.md
cargo-fuzz	Rust	Rust native fuzzing with libFuzzer backend	skills/cargo-fuzz/SKILL.md
Atheris	Python	Python coverage-guided fuzzing	skills/atheris/SKILL.md
Ruzzy	Ruby	Ruby coverage-guided fuzzing	skills/ruzzy/SKILL.md

Techniques

Technique	Purpose	Skill Path
Harness Writing	Writing effective fuzzing harnesses	skills/harness-writing/SKILL.md
Coverage Analysis	Measuring and improving code coverage	skills/coverage-analysis/SKILL.md
Fuzzing Dictionary	Creating effective fuzzing dictionaries	skills/fuzzing-dictionary/SKILL.md
Fuzzing Obstacles	Overcoming common fuzzing barriers	skills/fuzzing-obstacles/SKILL.md
AddressSanitizer	Memory error detection with ASan	skills/address-sanitizer/SKILL.md

Static Analysis

Tool	Purpose	Skill Path
Semgrep	Fast pattern-matching security scans	skills/semgrep/SKILL.md
CodeQL	Deep semantic code analysis	skills/codeql/SKILL.md

Cryptographic Testing

Tool	Purpose	Skill Path
Wycheproof	Test vectors for crypto implementations	skills/wycheproof/SKILL.md
Constant-Time Testing	Verify constant-time crypto properties	skills/constant-time-testing/SKILL.md

Infrastructure

Tool	Purpose	Skill Path
OSS-Fuzz	Google's continuous fuzzing service	skills/ossfuzz/SKILL.md

Meta

Tool	Purpose	Skill Path
Generator	Generate new skills from the Testing Handbook	skills/testing-handbook-generator/SKILL.md

Workflow

Starting a fuzzing campaign

1. Choose a fuzzer based on your target language (see Fuzzers table)
2. Write a harness using the harness-writing skill
3. Build with sanitizers (AddressSanitizer recommended as baseline)
4. Create a seed corpus with representative inputs
5. Run the campaign and monitor coverage
6. Analyze coverage to find uncovered code and improve the harness
7. Triage crashes and deduplicate findings

Setting up CI/CD testing

1. OSS-Fuzz for open-source projects (continuous fuzzing)
2. Semgrep + CodeQL for static analysis in PRs
3. Wycheproof test vectors for crypto validation

Quick Start by Language

Language	Fuzzer	Harness	Sanitizer
C/C++	libFuzzer or AFL++	LLVMFuzzerTestOneInput	ASan + UBSan
Rust	cargo-fuzz	fuzz_target! macro	Built-in sanitizers
Python	Atheris	atheris.FuzzedDataProvider	N/A
Ruby	Ruzzy	ruzzy harness pattern	N/A

Source Material

Generated from the Trail of Bits Application Security Testing Handbook using the testing-handbook-generator meta-skill.