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

• Choose a fuzzer based on your target language (see Fuzzers table)

• Write a harness using the harness-writing skill

• Build with sanitizers (AddressSanitizer recommended as baseline)

• Create a seed corpus with representative inputs

• Run the campaign and monitor coverage

• Analyze coverage to find uncovered code and improve the harness

• Triage crashes and deduplicate findings

Setting up CI/CD testing

• OSS-Fuzz for open-source projects (continuous fuzzing)

• Semgrep + CodeQL for static analysis in PRs

• 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.