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-auth-and-jwt-abusegit 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-auth-and-jwt-abuse)<a href="https://agentmods.dev/skills/yaklang/hack-skills/api-auth-and-jwt-abuse"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/api-auth-and-jwt-abuse/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-auth-and-jwt-abuse"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/api-auth-and-jwt-abuse.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket warn
- Snyk fail
- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Tool Misuse · line 73 Tool defaults are unsafe or overly permissive (e.g. disabled TLS verification, no authentication, world-writable permissions). Unsafe defaults widen the attack surface.Fix: Override unsafe defaults with secure settings (verify=True, auth required, restrictive permissions). Review and harden all tool configurations.
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 | $0.00041 | $0.00594 |
| Opus 5 | $0.00020 | $0.00297 |
| Sonnet 5 | $0.00008 | $0.00119 |
| Haiku 4.5 | $0.00004 | $0.00059 |
Grade A, and why
api-auth-and-jwt-abuse 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 10d 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
4 near-identical copies found in the catalogue:
- api-auth-and-jwt-abuse — 100% identical, 0 lines differ
- api-auth-and-jwt-abuse — 100% identical, 0 lines differ
- api-auth-and-jwt-abuse — 100% identical, 0 lines differ
- api-auth-and-jwt-abuse — 97% identical, 4 lines differ
What it actually says
SKILL: API Auth and JWT Abuse — Token Trust, Header Tricks, and Rate Limits
AI LOAD INSTRUCTION: Use this skill when APIs rely on JWT, bearer tokens, API keys, or weak request identity signals. Focus on token trust boundaries, claim misuse, header spoofing, and rate-limit bypass.
1. TOKEN TRIAGE
Inspect:
alg,kid,jku,x5u- role, org, tenant, scope, or privilege claims
- issuer and audience mismatches
- reuse of mobile and web tokens across products
2. QUICK ATTACK PICKS
| Pattern | First Test |
|---|---|
alg:none acceptance |
unsigned token with trailing dot |
| RS256 confusion | switch to HS256 using public key as secret |
kid lookup trust |
path traversal or injection in kid |
| remote key fetch trust | attacker-controlled jku or x5u |
| weak secret | offline crack with targeted wordlists |
3. HIDDEN FIELDS AND BATCH ABUSE
Mass assignment field picks
role
isAdmin
admin
verified
plan
tier
permissions
org
owner
Rate limit and batch abuse picks
X-Forwarded-For: 1.2.3.4
X-Real-IP: 5.6.7.8
Forwarded: for=9.9.9.9
GraphQL or JSON batch abuse candidates:
- arrays of login mutations
- bulk object fetches with varying IDs
- repeated password reset or verification calls in one request
4. RATE LIMIT BYPASS FAMILIES
X-Forwarded-For
X-Real-IP
Forwarded
User-Agent rotation
Path case / slash variants
5. NEXT ROUTING
- For GraphQL batching and hidden parameters: graphql and hidden parameters
- For default credential and brute-force planning: authentication bypass
- For full JWT and OAuth depth: jwt oauth token attacks
- For OAuth or OIDC configuration flaws in browser and SSO flows: oauth oidc misconfiguration
- For credentialed browser reads and origin trust bugs: cors cross origin misconfiguration
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.
- 10d ago First seen · 76 lines · 41 tokens per session scan A f77a15d45c31
api-auth-and-jwt-abuse is a skill published in the GitHub repository yaklang/hack-skills (2,143 stars, last pushed 2mo ago), licensed MIT. It adds 41 tokens to every session and 594 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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