Security Expert Skill

When to Use

• Implementing authentication or authorization
• Reviewing code for security vulnerabilities
• Setting up security configurations
• Handling sensitive data
• Implementing encryption or hashing
• Configuring CORS, CSP, or security headers
• Reviewing dependencies for vulnerabilities
• Implementing multi-tenancy or data isolation

Project Context Discovery

1. Check .agents/memory/ for security architecture notes and project facts
2. Review the applicable AGENTS.override.md / AGENTS.md chain and any explicitly configured fallback instruction file; include CLAUDE.md only for Claude-specific rules
3. Identify security patterns and tools
4. Check for [project]-security-expert skill

Core Security Principles

Authentication & Authorization

Authentication: Secure password hashing (bcrypt/argon2), JWT management, session security, MFA, OAuth/SSO

Authorization: RBAC, permission checks on all endpoints, resource-level auth, multi-tenancy enforcement

Input Validation

• DTOs with class-validator
• Sanitize user input
• Prevent NoSQL/SQL injection
• Parameterized queries

Data Protection

• Encryption at rest and in transit
• Passwords hashed (never plaintext)
• Environment variables for secrets
• No secrets in code

Security Headers

• X-Content-Type-Options: nosniff
• X-Frame-Options: DENY
• Strict-Transport-Security
• Content Security Policy

OWASP Top 10 Quick Reference

1. Broken Access Control: Verify auth on all endpoints
2. Cryptographic Failures: Strong encryption, proper hashing
3. Injection: Parameterized queries, input validation
4. Insecure Design: Security by design, threat modeling
5. Security Misconfiguration: Secure defaults, remove unused features
6. Vulnerable Components: Keep dependencies updated
7. Authentication Failures: Strong passwords, MFA, brute force protection
8. Integrity Failures: Secure CI/CD, code signing
9. Logging Failures: Comprehensive logging, monitoring
10. SSRF: Validate URLs, whitelist domains

Security Checklist Summary

• Passwords hashed (bcrypt/argon2)
• All endpoints protected
• Multi-tenancy enforced
• All inputs validated
• Encryption at rest/transit
• Security headers configured
• CORS properly configured
• Dependencies up to date

For complete authentication/authorization patterns, input validation examples, OWASP prevention techniques, framework-specific security (React/Next.js/NestJS), MongoDB security, AWS security, and detailed security checklists, see: references/full-guide.md