Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/woohyun212/security-skillnpx agentmods add skills/woohyun212/security-skill/testing-handbookWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/woohyun212/security-skill/testing-handbook)<a href="https://agentmods.dev/skills/woohyun212/security-skill/testing-handbook"><img src="https://agentmods.dev/badge/skills/woohyun212/security-skill/testing-handbook.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00036 | $0.03393 |
| Opus 5 | $0.00018 | $0.01697 |
| Sonnet 5 | $0.00007 | $0.00679 |
| Haiku 4.5 | $0.00004 | $0.00339 |
Grade A, and why
testing-handbook scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 297 lines — stays where its author put it; the contents beside it link to each section on GitHub.
What this skill does
Guides structured security testing across three pillars: Fuzzing (AFL++, libFuzzer, Honggfuzz), Sanitizers (ASan, MSan, UBSan, TSan), and Static Analysis (Semgrep, CodeQL, Clang Static Analyzer). Covers harness writing, corpus management, crash triage, sanitizer compilation flags, output interpretation, and mapping discovered vulnerabilities to MITRE ATT&CK techniques. Adapted from the Trail of Bits Testing Handbook methodology.
When to use
- Before shipping a parser, deserializer, network handler, or any code that processes untrusted input
- When auditing a C/C++ codebase for memory safety issues (buffer overflows, use-after-free, uninitialized reads)
- When a code review or SAST scan flags a high-risk function that needs empirical validation
- When setting up a continuous fuzzing pipeline (CI integration, corpus persistence)
- When triage is needed on a crash or sanitizer report of unknown severity
Prerequisites
| Tool | Install | Notes |
|---|---|---|
| AFL++ | apt install afl++ or build from source |
Recommended fuzzer for binary targets |
| libFuzzer | Bundled with Clang/LLVM (≥ 6.0) | In-process fuzzer; requires harness |
| Honggfuzz | apt install honggfuzz or go install github.com/google/honggfuzz |
Good for network/persistent mode |
| Clang/LLVM | apt install clang |
Required for sanitizer instrumentation |
| Semgrep | pip install semgrep |
SAST; free community rules available |
| CodeQL CLI | Download from github.com/github/codeql-action | SAST; requires CodeQL database build |
| Clang Static Analyzer | Bundled with Clang | Lightweight SAST via scan-build |
Inputs
| Item | Description | Example |
|---|---|---|
TARGET_FUNCTION |
Function(s) or code path(s) to test | parse_http_request(), deserialize_json() |
TARGET_BINARY |
Compiled target or library under test | ./build/libparser.so, ./bin/server |
CORPUS_DIR |
Directory of seed inputs for the fuzzer | ./corpus/, ./tests/fixtures/ |
LANGUAGE |
Primary language of the target | C, C++, Rust, Go |
BUILD_FLAGS |
Sanitizer and instrumentation flags | -fsanitize=address,undefined -g |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 6d ago First seen · 297 lines · 36 tokens per session scan A 166571aa9ee6
testing-handbook is a skill published in the GitHub repository woohyun212/security-skill (21 stars, last pushed 4mo ago), licensed MIT. It adds 36 tokens to every session and 3,393 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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