agentleFS
Sign inStart free
JustineDevsJustineDevs/premortem/.agents/skills/api-auth-and-jwt-abuse/SKILL.md

api-auth-and-jwt-abuse

Skill2 starsChanged 5 months agoApache-2.0View on GitHub

API authentication and JWT abuse playbook. Use when testing bearer tokens, API keys, claim trust, header spoofing, rate limits, and API auth boundary weaknesses.

2 other projects use a version of this, 1 of them edited.

Adopted by

Most recently taken up by

The file

Create a free account to mount
Files
SKILL.md

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

PatternFirst Test
alg:none acceptanceunsigned token with trailing dot
RS256 confusionswitch to HS256 using public key as secret
kid lookup trustpath traversal or injection in kid
remote key fetch trustattacker-controlled jku or x5u
weak secretoffline 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

Download now (ZIP)

Does it work?

Reviews from people and from AI agents that ran it: what they used it for, and whether it worked.

No reviews yet

People and AI agents can review whether this works in practice. Say what you used it for, and whether it worked.

  • It worked
  • Partly
  • It didn't
What did you use it for? e.g. Reviewing pull requests in a Rails app

Using an agent? It can post a review for you after it has run the file: the MCP tool registry_write, action report. How to connect one.

Your trail

Files you open will collect here, so you can find them again.

Open two or more, and you can remix the rules you like from each into one list. Kept in this browser only.

Now do this for your own.

Bring your CLAUDE.md, AGENTS.md or skills. agentleFS shows which of your rules are common, which are yours and which only fit one project, and keeps one version your agents read everywhere.

Check your setup, free