HackSkills is an organized knowledge base of installable skills that gives AI agents practical security knowledge across areas such as web security, privilege escalation, reverse engineering, and digital forensics. It is intended for bug bounty work, penetration testing, CTF competitions, and authorized security research. The catalogue entries are the project's own master, category, and topic skills.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add yaklang/hack-skills --skill api-secgit clone --depth 1 https://github.com/yaklang/hack-skillsWrote 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/yaklang/hack-skills/api-sec)<a href="https://agentmods.dev/skills/yaklang/hack-skills/api-sec"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/api-sec/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/yaklang/hack-skills/api-sec"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/api-sec.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
- NVIDIA SkillSpector pass
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 | $0.00599 |
| Opus 5.5 | $0.00014 | $0.00240 |
| Sonnet 5.5 | $0.00007 | $0.00120 |
| Haiku 4.5 | $0.00004 | $0.00060 |
Grade A, and why
api-sec 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 1mo 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.
Copies of this mod
How it starts
The opening of the file, as written. The whole thing — 49 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Security Router
This is the routing entry point for API security testing.
Use this skill first to decide whether the API issue is mostly recon/docs, object authorization, token trust, or GraphQL/hidden parameters, then route to a deeper topic skill.
When to Use
- The target exposes REST APIs, mobile backends, or GraphQL endpoints
- You need to define API testing order before going into specific topics
- You want to handle object authorization, JWT, GraphQL, and hidden fields as separate tracks
Skill Map
- API Recon and Docs: OpenAPI, Swagger, version drift, hidden documentation
- API Authorization and BOLA: BOLA, BFLA, method abuse, hidden writable fields
- API Auth and JWT Abuse: bearer token, header trust, claim abuse, rate-limit bypass
- GraphQL and Hidden Parameters: introspection, batching, undocumented fields, hidden parameters
Quick Triage
| Observation | Route |
|---|---|
| Swagger or OpenAPI is present | api-recon-and-docs |
| IDs appear in URL, JSON, headers, or GraphQL args | api-authorization-and-bola |
| JWT token visible in traffic | api-auth-and-jwt-abuse |
/graphql or batched JSON arrays are present |
graphql-and-hidden-parameters |
| Registration, login, or profile updates accept extra fields | api-authorization-and-bola then api-auth-and-jwt-abuse |
Recommended Flow
- Start with exposed endpoints and documentation assets
- Then evaluate object-level and function-level authorization
- Then evaluate token, header, signature, and rate-limit boundaries
- If GraphQL or complex JSON is present, continue with hidden fields and schema abuse
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.
- 1mo ago First seen · 49 lines · 36 tokens per session scan A d3da8c0ed9b1
api-sec is a skill published in the GitHub repository yaklang/hack-skills (2,460 stars, last pushed 1mo ago), licensed MIT. It adds 36 tokens to every session and 599 once invoked, about $0.0001 per session on Opus 5.5. 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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