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audit-auth

Testing & Quality
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Audit authentication and session-management code for common issues — weak JWT config, session fixation, password-handling flaws, insecure cookies, broken OAuth flows, and missing auth checks on routes. Use when the user asks to review auth code or when source-aware scanning targets login/session/token handling.

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How to use this skill

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Source SKILL.md: https://github.com/vigolium/vigolium/blob/HEAD/internal/resources/olium/skills/audit-auth/SKILL.md

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Authentication & Session Code Audit

You are auditing authentication and session-management code. Your goal is to identify concrete, reproducible vulnerabilities — not style nits. Each issue you raise must map to a CWE and a specific file + line range, and must be persisted via the report_finding tool.

Scope — what to look for

Work through these in order; some targets will be irrelevant (skip and say so in your final summary rather than fabricating findings):

1. JWT / token handling

  • alg=none accepted by the verifier (CWE-327)
  • Secret reused for HMAC and RSA (key confusion, CWE-347)
  • Hard-coded secrets or secrets pulled from non-secret sources
  • Missing iss, aud, exp validation (CWE-345)
  • Tokens logged at INFO level (CWE-532)

2. Session management

  • Session IDs derived from user input or predictable sources (CWE-330)
  • No session rotation on privilege change (CWE-384 session fixation)
  • Cookies missing HttpOnly, Secure, or SameSite (CWE-1004)
  • Long or unbounded session lifetime

3. Password handling

  • Plaintext storage or fast hashes (MD5/SHA1/SHA256 without KDF) (CWE-916)
  • Passwords in URL query strings, logs, or error messages
  • Timing-unsafe comparison of password hashes (CWE-208)
  • No rate limiting on login (CWE-307)

4. OAuth / OIDC

  • Missing state / PKCE (CWE-352 CSRF on auth flow)
  • Open redirect on callback (CWE-601)
  • redirect_uri not validated against allowlist
  • Token exposure via referer or fragment-in-GET

5. Route-level auth

  • Handlers that forget to call the auth middleware
  • Role checks on client-supplied fields (e.g., trusting req.body.role)
  • IDOR: authorization based on URL param without ownership check (CWE-639)

Recommended workflow

  1. Inventory: use glob to find auth-related files. Typical patterns:
    • **/auth/**, **/session*, **/login*, **/oauth*, **/middleware*, **/jwt*
  2. Read the entry points: login handler, session middleware, token verifier.
  3. Grep for red flags:
    • alg.*none, jwt.Parse[^A-Z] (missing key func)
    • md5|sha1 in a hashing context
    • bcrypt\.CompareHashAndPassword — good; absence of it near a login handler — suspicious
    • httpOnly\s*:\s*false, secure\s*:\s*false
    • res.redirect.*req\. (open redirect pattern)
  4. For each concrete finding, call report_finding with:
    • severity: critical | high | medium | low
    • title: short, specific (e.g., "JWT verifier accepts alg=none")
    • cwe_id: CWE-xxx
    • source_file: relative path
    • description: 1-3 sentences of what + why
    • remediation: 1-2 sentences of fix

Output expectations

  • At least one line of summary per file audited (even if clean).
  • Every finding persisted via report_finding — do NOT just enumerate in your final text message.
  • If you run out of context (very large codebase), audit the most critical paths first: JWT verification, session creation, login handler. Skip admin panels and internal tools unless explicitly in scope.
  • Do NOT flag speculative issues ("this could theoretically be…") — only concrete code paths with file + line.