Checking Session Security
Overview
Audit session management implementations in web applications to identify vulnerabilities including session fixation (CWE-384), insufficient session expiration (CWE-613), and cleartext transmission of session tokens (CWE-319).
Prerequisites
- Application source code accessible in
${CLAUDE_SKILL_DIR}/ - Session management code locations identified (auth modules, middleware, session stores)
- Framework and language identified (Express.js, Django, Spring Boot, Rails, ASP.NET, etc.)
- Session configuration files available (
session.config.*,settings.py,application.yml) - Write permissions for reports in
${CLAUDE_SKILL_DIR}/security-reports/
Instructions
- Locate session management code by searching for patterns:
**/auth/**,**/session/**,**/middleware/**, and framework-specific files (settings.py,application.yml,web.config). - Analyze session ID generation: verify use of a cryptographically secure random generator with at least 128 bits of entropy. Flag predictable patterns such as
Date.now(),Math.random(), sequential IDs, or timestamp-based tokens (CWE-330). - Check session fixation protections: confirm the session ID is regenerated after authentication (
req.session.regenerate()in Express,request.session.cycle_key()in Django). Flag any login handler that setsauthenticated = truewithout regenerating the session ID. - Validate cookie security attributes: verify
HttpOnly(prevents XSS-based token theft),Secure(HTTPS-only transmission),SameSite=Lax|Strict(CSRF mitigation), and__Host-/__Secure-prefix usage. Flag any missing attribute. - Review session expiration: check idle timeout (recommend 15-30 min for sensitive apps), absolute timeout (recommend 4-8 hours), and sliding window configuration. Flag sessions without any expiration.
- Audit session invalidation: verify logout handlers destroy server-side session state and clear client cookies. Confirm password reset and privilege escalation flows invalidate existing sessions.
- Inspect session storage: flag in-memory stores in production (no persistence across restarts), unencrypted session data at rest, and missing integrity checks on session payloads (e.g., unsigned JWT session tokens).
- Identify attack vectors: assess exposure to session fixation, CSRF via session riding, replay attacks from stolen tokens, and session prediction from weak ID generation.
- Produce the session security report at
${CLAUDE_SKILL_DIR}/security-reports/session-security-YYYYMMDD.mdwith per-finding severity, CWE mapping, vulnerable code snippet, and remediated code example.
See ${CLAUDE_SKILL_DIR}/references/implementation.md for the detailed implementation guide. See ${CLAUDE_SKILL_DIR}/references/critical-findings.md for example vulnerability patterns with before/after code.
Output
- Session Security Report:
${CLAUDE_SKILL_DIR}/security-reports/session-security-YYYYMMDD.mdwith findings by severity - Cookie Attribute Matrix: per-cookie compliance table (HttpOnly, Secure, SameSite, prefix)
- Vulnerable Code Listings: each finding with file path, line number, vulnerable snippet, and fix
- Framework-Specific Remediation: configuration changes tailored to the detected framework
Error Handling
| Error | Cause | Solution |
|---|---|---|
No session handling code found in ${CLAUDE_SKILL_DIR}/ | Unusual file structure or framework | Search for framework-specific patterns; request explicit file paths |
| Unknown session framework | Custom or uncommon session library | Apply fundamental session security principles; note limited framework-specific guidance |
| Cannot analyze minified/compiled code | Production bundles instead of source | Request unminified source code; document limitation |
| Non-standard session implementation | Custom session management bypassing framework | Apply extra scrutiny; custom implementations are higher risk (CWE-384, CWE-613) |
| Session config in environment variables, not code | Externalized configuration | Request .env.example or deployment config documentation |
Examples
- "Audit session cookie flags and rotation logic for fixation and CSRF risks in the Express.js application."
- "Review logout and password reset flows to confirm sessions are invalidated correctly and old tokens cannot be replayed."
- "Check session ID generation entropy and storage backend security for the Django application."
Resources
- OWASP Session Management Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Session_Management_Cheat_Sheet.html
- CWE-384 Session Fixation: https://cwe.mitre.org/data/definitions/384.html
- CWE-613 Insufficient Session Expiration: https://cwe.mitre.org/data/definitions/613.html
- CWE-319 Cleartext Transmission: https://cwe.mitre.org/data/definitions/319.html
- NIST 800-63B Digital Authentication: https://pages.nist.gov/800-63-3/sp800-63b.html
${CLAUDE_SKILL_DIR}/references/critical-findings.md-- example vulnerability patterns${CLAUDE_SKILL_DIR}/references/errors.md-- full error handling reference- https://intentsolutions.io