Security Checklist#

Quick reference for web application security. Use alongside the security-and-hardening skill.

Table of Contents#

• Pre-Commit Checks
• Authentication
• Authorization
• Input Validation
• Security Headers
• CORS Configuration
• Data Protection
• Dependency Security
• Error Handling
• OWASP Top 10 Quick Reference

Pre-Commit Checks#

• [ ] No secrets in code (git diff --cached | grep -i "password\|secret\|api_key\|token")
• [ ] .gitignore covers: .env, .env.local, *.pem, *.key
• [ ] .env.example uses placeholder values (not real secrets)

Authentication#

• [ ] Passwords hashed with bcrypt (≥12 rounds), scrypt, or argon2
• [ ] Session cookies: httpOnly, secure, sameSite: 'lax'
• [ ] Session expiration configured (reasonable max-age)
• [ ] Rate limiting on login endpoint (≤10 attempts per 15 minutes)
• [ ] Password reset tokens: time-limited (≤1 hour), single-use
• [ ] Account lockout after repeated failures (optional, with notification)
• [ ] MFA supported for sensitive operations (optional but recommended)

Authorization#

• [ ] Every protected endpoint checks authentication
• [ ] Every resource access checks ownership/role (prevents IDOR)
• [ ] Admin endpoints require admin role verification
• [ ] API keys scoped to minimum necessary permissions
• [ ] JWT tokens validated (signature, expiration, issuer)

Input Validation#

• [ ] All user input validated at system boundaries (API routes, form handlers)
• [ ] Validation uses allowlists (not denylists)
• [ ] String lengths constrained (min/max)
• [ ] Numeric ranges validated
• [ ] Email, URL, and date formats validated with proper libraries
• [ ] File uploads: type restricted, size limited, content verified
• [ ] SQL queries parameterized (no string concatenation)
• [ ] HTML output encoded (use framework auto-escaping)
• [ ] URLs validated before redirect (prevent open redirect)

Security Headers#

Content-Security-Policy: default-src 'self'; script-src 'self'
Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
X-XSS-Protection: 0  (disabled, rely on CSP)
Referrer-Policy: strict-origin-when-cross-origin
Permissions-Policy: camera=(), microphone=(), geolocation=()

CORS Configuration#

// Restrictive (recommended)
cors({
  origin: ['https://yourdomain.com', 'https://app.yourdomain.com'],
  credentials: true,
  methods: ['GET', 'POST', 'PUT', 'PATCH', 'DELETE'],
  allowedHeaders: ['Content-Type', 'Authorization'],
})

// NEVER use in production:
cors({ origin: '*' })  // Allows any origin

Data Protection#

• [ ] Sensitive fields excluded from API responses (passwordHash, resetToken, etc.)
• [ ] Sensitive data not logged (passwords, tokens, full CC numbers)
• [ ] PII encrypted at rest (if required by regulation)
• [ ] HTTPS for all external communication
• [ ] Database backups encrypted

Dependency Security#

# Audit dependencies
npm audit

# Fix automatically where possible
npm audit fix

# Check for critical vulnerabilities
npm audit --audit-level=critical

# Keep dependencies updated
npx npm-check-updates

Error Handling#

// Production: generic error, no internals
res.status(500).json({
  error: { code: 'INTERNAL_ERROR', message: 'Something went wrong' }
});

// NEVER in production:
res.status(500).json({
  error: err.message,
  stack: err.stack,         // Exposes internals
  query: err.sql,           // Exposes database details
});

OWASP Top 10 Quick Reference#