<objective> This skill audits authentication and authorization implementations end to end: JWT signing algorithm, expiration, refresh, and storage; session storage, expiry, regeneration, and fixation; OAuth2 PKCE, state parameter, and redirect validation; password hashing algorithm, strength rules, and reset flow; and MFA implementation, backup codes, and recovery.

It runs a fixed workflow — detect the auth implementation, scan for known anti-patterns, verify cryptographic choices, check token/session lifecycle, and audit authorization logic (RBAC/ABAC) — checking for vulnerabilities such as JWT signed with none, undersized JWT secrets, missing/too-long token expiration, refresh tokens in localStorage, session fixation, missing CSRF protection, and OAuth flows missing PKCE or the state parameter. </objective>

Auth Audit Skill

Overview

Comprehensive audit of authentication and authorization implementations.

Audit Categories

Category	Checks
JWT	Signing algo, expiration, refresh, storage
Sessions	Storage, expiry, regeneration, fixation
OAuth2	PKCE, state param, redirect validation
Passwords	Hashing algo, strength rules, reset flow
MFA	Implementation, backup codes, recovery

Workflow

1. Detect auth implementation (JWT, sessions, OAuth)
2. Scan for known anti-patterns
3. Verify cryptographic choices
4. Check token/session lifecycle
5. Audit authorization logic (RBAC, ABAC)

Common Vulnerabilities

• JWT signed with none algorithm
• JWT secret too short (< 256 bits)
• No token expiration or too long
• Refresh tokens stored in localStorage
• Session fixation after login
• Missing CSRF protection
• OAuth without PKCE for public clients
• Missing state parameter in OAuth flow

References

• Auth Patterns
• Auth Checklist