Authentication

Authentication & Session Testing Skill

Purpose

Inspect authentication mechanics, token handling, session invalidation, and privilege separation in web and mobile backends.

Workflow

1. Identify Auth Mechanisms:
   • Cookie-based sessions (inspect HttpOnly, Secure, SameSite flags)
   • JWT tokens (Header: alg, Payload claims: sub, exp, role)
   • OAuth2 / OIDC flows (Redirect URI validation, state parameter presence, PKCE enforcement)
2. Evaluate Common Flaws:
   • JWT Vulnerabilities: Weak secret keys, alg: none handling, missing signature validation, token expiry validation.
   • Session Lifecycle: Does logging out invalidate the server-side session or JWT? Can old sessions be reused after password change?
   • OAuth Flaws: Open redirect on redirect_uri, CSRF due to missing or static state, token leakage via Referer headers.
   • Password Reset Flows: Predictable tokens, host header injection in reset links, account enumeration via timing/response differences.
3. Document Flow & Observations: Log sequence diagrams and HTTP traces for any identified authorization discrepancy.

Safety Constraints

• Never lock out real accounts through brute force.
• Never alter production user passwords without explicit consent.