Reviewing Security

Reviewing Security

Security Reviewer Process

1. Read the diff. Run git diff HEAD~1 (or the applicable range) to see what changed.

2. Identify the attack surface. Determine what the changed code touches: user input, authentication, authorization, data storage, external services, file system, command execution, serialization, or network communication.

3. Apply OWASP Top 10 checks to every changed file:

   • Injection — SQL, NoSQL, OS command, LDAP. Is user input interpolated into queries or commands without parameterization?
   • Broken Authentication — Weak password handling, missing rate limiting, session fixation, credential exposure in logs.
   • Sensitive Data Exposure — Secrets in code, PII in logs, missing encryption, overly broad API responses.
   • XSS — User input rendered without escaping in HTML, JavaScript, or template contexts.
   • CSRF — State-changing operations without token validation.
   • Insecure Deserialization — Untrusted data passed to deserializers without validation.
   • Missing Access Control — Authorization checks absent or bypassable, IDOR vulnerabilities, privilege escalation paths.
   • Security Misconfiguration — Debug mode in production, overly permissive CORS, missing security headers, default credentials.

4. Check for more vulnerabilities:

   • Hardcoded secrets — API keys, passwords, tokens, connection strings in source code or configuration committed to version control.
   • Command injection — User input passed to shell execution, exec, spawn, or eval without sanitization.
   • Path traversal — User-controlled input used in file paths without validation (e.g., ../../../etc/passwd).
   • Unsafe regex — Regular expressions vulnerable to ReDoS (catastrophic backtracking with user-controlled input).
   • Missing input validation — Data crossing system boundaries (HTTP requests, file uploads, environment variables) without schema validation or sanitization.

5. Search beyond the diff. If the diff introduces a pattern that could be vulnerable, grep the broader codebase for similar patterns.

Security Severity Classification

CRITICAL — Hard Gate

The code MUST NOT ship with these findings. Examples:

• Hardcoded secrets or credentials
• SQL/command injection with user-controlled input
• Authentication bypass
• Missing authorization on sensitive endpoints

HIGH — Hard Gate

The code MUST NOT ship with these findings. Examples:

• XSS in user-facing output
• CSRF on state-changing endpoints
• Sensitive data in logs

MEDIUM

Moderate risk, should be addressed soon. Examples:

• Overly permissive CORS configuration
• Missing rate limiting on auth endpoints
• Weak cryptographic choices

LOW

Minor risk or defense-in-depth improvement. Examples:

• Missing security headers on non-sensitive endpoints
• Informational leakage in error messages