Security Code Review Tips: Essential Guide for Engineering Teams

Security vulnerabilities in code can lead to devastating breaches, data theft, and regulatory penalties. This comprehensive guide provides engineering teams with practical security code review techniques, checklists, and tools to identify and prevent security issues before they reach production.

Essential Security Review Areas

Effective security code review requires systematic examination of specific vulnerability categories. Here are the critical areas every reviewer should focus on:

Input Validation and Sanitization

Input validation is the first line of defense against injection attacks. Review code for:

• SQL Injection: Check for parameterized queries, ORM usage, and dynamic query construction
• XSS Prevention: Ensure proper output encoding and Content Security Policy implementation
• Command Injection: Look for unsafe system calls and shell command execution
• Path Traversal: Validate file path inputs and restrict access to authorized directories

Authentication and Session Management

Authentication flaws can lead to complete system compromise. Key review points:

• Password Security: Verify strong hashing algorithms (bcrypt, Argon2, PBKDF2)
• Session Security: Check for secure session tokens, proper timeout, and secure storage
• Multi-Factor Authentication: Ensure MFA implementation follows security best practices
• OAuth/SSO: Review integration security, token validation, and scope limitations

Authorization and Access Control

Authorization determines what authenticated users can access. Review for:

• Principle of Least Privilege: Users should have minimal necessary permissions
• Role-Based Access Control: Verify proper role assignment and inheritance
• Resource-Level Authorization: Check authorization at the data/object level
• Privilege Escalation: Look for potential horizontal/vertical privilege escalation

Security Code Review Checklist

Use this comprehensive checklist during security-focused code reviews:

Common Security Anti-Patterns to Watch For

Recognize these common security mistakes during code review:

1. Inadequate Input Validation

// Direct SQL query construction
const query = "SELECT * FROM users WHERE id = " + userId;
db.execute(query);

// Parameterized query
const query = "SELECT * FROM users WHERE id = ?";
db.execute(query, [userId]);

2. Insufficient Authorization Checks

// Only checking authentication
if (user.isAuthenticated) {
  return getUserData(requestedUserId);
}

// Check both authentication and authorization
if (user.isAuthenticated && canAccessUser(user.id, requestedUserId)) {
  return getUserData(requestedUserId);
}

Automated Security Tools Integration

Complement manual reviews with automated security analysis:

Static Application Security Testing (SAST)

• SonarQube Security Rules: Comprehensive language-specific security rule sets
• Checkmarx: Enterprise-grade SAST with detailed vulnerability reporting
• Semgrep: Fast, customizable static analysis with security rule packs
• CodeQL: GitHub's semantic code analysis for security vulnerabilities

Dynamic Application Security Testing (DAST)

• OWASP ZAP: Free dynamic security testing with CI/CD integration
• Burp Suite: Professional web application security testing
• Netsparker: Automated vulnerability scanning with low false positives
• Rapid7 InsightAppSec: Cloud-based dynamic security testing

Dependency Security Review

Third-party dependencies are common attack vectors. Review for:

• Known Vulnerabilities: Use tools like npm audit, Snyk, or OWASP Dependency Check
• License Compliance: Ensure dependencies meet your organization's license requirements
• Maintenance Status: Avoid unmaintained or deprecated libraries
• Scope Minimization: Only include necessary dependencies and features

Building a Security-First Review Culture

Establish processes that make security review systematic and sustainable:

Security Champions Program

• Designate security-focused reviewers on each development team
• Provide regular security training and threat modeling workshops
• Create security review guidelines and team-specific playbooks
• Establish escalation paths for complex security concerns

Review Process Integration

• Security Labels: Tag security-sensitive PRs for specialized review
• Required Reviewers: Mandate security champion approval for sensitive changes
• Security Gates: Block merges until security tools pass and reviews complete
• Threat Modeling: Require threat analysis for significant feature additions

Measuring Security Review Effectiveness

Track metrics to improve your security review process:

Frequently Asked Questions