Claude Skills for Security Auditing: A Comprehensive Review

Security Skills: The Deep Bench

Security auditing is where Claude Skills show their most dramatic advantage over raw prompting. Security work is procedural, detail-oriented, and has zero tolerance for missed steps — exactly the kind of work that benefits from structured instruction files.

Static Analysis Skills

semgrep — Runs Semgrep static analysis scans with parallel subagents. Supports "run all" (full ruleset coverage including security-and-quality + experimental suites) and "important only" (high-precision security findings). Automatically detects project languages and spawns parallel workers for multi-language codebases.

codeql — CodeQL's interprocedural data flow and taint tracking analysis. Builds databases, runs security queries, and processes SARIF output. Supports both broad scans and targeted high-precision modes.

Vulnerability-Specific Skills

c-review — Comprehensive C/C++ security review targeting memory corruption, integer overflows, race conditions, and platform-specific vulnerabilities. Essential for native code audits.

constant-time-analysis — Detects timing side-channel vulnerabilities in cryptographic code. Catches secret-dependent branches, division on secrets, and variable-time operations across 12 programming languages.

insecure-defaults — Finds fail-open patterns: hardcoded secrets, weak authentication defaults, permissive security configurations that allow apps to run insecurely in production.

Smart Contract Auditing

The skill collection includes specialized scanners for every major blockchain platform:

• solana-vulnerability-scanner — 6 critical vulnerability patterns in Solana/Anchor programs
• cairo-vulnerability-scanner — StarkNet-specific issues including felt252 overflow
• cosmos-vulnerability-scanner — 51 patterns across SDK modules, IBC, and CosmWasm
• algorand-vulnerability-scanner — 11 patterns including rekeying and unchecked fees
• substrate-vulnerability-scanner — 7 patterns in Polkadot/FRAME pallets
• ton-vulnerability-scanner — FunC contract vulnerabilities

Audit Workflow Skills

audit-context-building — Enables line-by-line code analysis to build deep architectural context before vulnerability hunting. This is the "understand before you attack" phase.

entry-point-analyzer — Identifies all state-changing entry points in a smart contract, categorized by access level (public, admin, role-restricted, contract-only).

fp-check — Verifies suspected security bugs to eliminate false positives. Produces TRUE POSITIVE or FALSE POSITIVE verdicts with documented evidence.

differential-review — Security-focused review of code changes. Calculates blast radius, checks test coverage for security-critical changes, and prevents security regressions.

Fuzzing Skills

A complete fuzzing toolkit:

• harness-writing — Techniques for writing effective fuzz targets across languages
• aflpp — AFL++ configuration for multi-core C/C++ fuzzing
• libfuzzer — LLVM-based coverage-guided fuzzing
• cargo-fuzz — Rust-specific fuzzing with libFuzzer backend
• atheris — Coverage-guided Python fuzzing

The Audit Playbook

A production security audit using skills follows this sequence:

1. audit-context-building — Understand the codebase architecture
2. entry-point-analyzer — Map the attack surface
3. semgrep + codeql — Automated vulnerability scanning
4. fp-check — Verify each finding
5. differential-review — Check recent changes for regressions
6. code-maturity-assessor — Score overall security posture

This systematic approach catches vulnerabilities that ad-hoc prompting would miss entirely.