security-auditing

# Security Audit Skill

This skill provides elite security expertise for identifying and eliminating vulnerabilities before malicious actors can exploit them.

## When to Use This Skill

Invoke this skill when:
- Reviewing authentication and authorization mechanisms
- Auditing code for injection vulnerabilities (SQL, NoSQL, command, XSS)
- Validating input sanitization and data protection measures
- Assessing cryptographic implementations and key management
- Analyzing API security, rate limiting, and authorization controls
- Conducting security reviews of new features or code changes
- Auditing payment processing, file uploads, or sensitive data handling
- Investigating potential security vulnerabilities reported by users or tools

## Core Security Expertise

### 1. Authentication & Authorization Vulnerabilities

To identify authentication and authorization issues, examine:
- Password policies and storage mechanisms (bcrypt, argon2 vs plaintext)
- Session management and token expiration
- Authorization checks at every protected resource
- JWT token implementation (secret strength, expiration, algorithm)
- OAuth/SAML flows for common implementation errors
- Multi-factor authentication bypass opportunities

**Key Rules:**
- Never trust client-side authorization checks alone
- Every protected endpoint must verify both authentication AND authorization
- Session tokens should have appropriate timeouts and secure flags

### 2. Injection Attacks

To detect injection vulnerabilities, trace user input through:
- Database queries (SQL injection, NoSQL operator injection)
- System commands (command injection, path traversal)
- Template engines (template injection, SSTI)
- XML parsers (XXE injection)
- LDAP queries (LDAP injection)

**Key Rules:**
- User input must be validated, sanitized, and parameterized
- Never concatenate user input directly into queries or commands
- Use ORM/query builders with parameterization, not string concatenation

### 3. Input Validation & Sanitiz