api-auth-and-jwt-abuse

api-auth-and-jwt-abuse is a skill for Claude Code, Codex from DorianGallo/hack-skills-local. It costs 41 tokens per session (594 once invoked), scanned A, a copy of api-auth-and-jwt-abuse, MIT.

A security testing playbook for API keys, bearer tokens, and JWTs. A JWT is a signed data token that often carries identity or permission claims.

In plain words
What is it for?
It is for testing token algorithms, roles, organizations, tenants, scopes, key lookups, remote keys, mass-assigned fields, forwarded IP headers, and bulk requests.
Why use it?
It helps find cases where an API trusts altered token claims, request headers, key references, or weak rate-limit signals.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit It is for testing token algorithms, roles, organizations, tenants, scopes, key lookups, remote keys, mass-assigned fields, forwarded IP headers, and bulk requests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/doriangallo/hack-skills-local/api-auth-and-jwt-abuse
Install

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.

Any agent
npx skills add DorianGallo/hack-skills-local --skill api-auth-and-jwt-abuse
Clone the repo
git clone --depth 1 https://github.com/DorianGallo/hack-skills-local

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for api-auth-and-jwt-abuse

README.md
[![agentmods](https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/api-auth-and-jwt-abuse/github.svg)](https://agentmods.dev/skills/doriangallo/hack-skills-local/api-auth-and-jwt-abuse)
Your own site
<a href="https://agentmods.dev/skills/doriangallo/hack-skills-local/api-auth-and-jwt-abuse"><img src="https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/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.

agentmods 80×15 button for api-auth-and-jwt-abuse

Your own site · 80×15
<a href="https://agentmods.dev/skills/doriangallo/hack-skills-local/api-auth-and-jwt-abuse"><img src="https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/api-auth-and-jwt-abuse.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 594 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

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.

ModelPer sessionOnce 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

Measured 12d ago against content hash f77a15d45c31, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

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 12d 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.

Origin

This is a copy

100% identical to api-auth-and-jwt-abuse — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/api-auth-and-jwt-abuse/SKILL.md · 76 lines

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

Changes

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.

  1. 12d ago First seen · 76 lines · 41 tokens per session scan A f77a15d45c31

Subscribe to this mod's changes

api-auth-and-jwt-abuse is a skill published in the GitHub repository DorianGallo/hack-skills-local (5 stars, last pushed 3mo 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. It is 100% identical to api-auth-and-jwt-abuse, differing in 0 lines, and is treated as a copy.

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