API Security

Security practices and patterns for protecting API endpoints from unauthorized access, ensuring proper authentication and authorization at multiple layers of the application stack.

Core Security Principles

Per-Handler Authentication

Each API endpoint should implement independent authentication checks rather than relying solely on middleware:

// Vulnerable: Middleware-only protection
export async function POST(request: Request) {
  // No auth check - relies on middleware
  return await updateData();
}

// Secure: Per-handler authentication
export async function POST(request: Request) {
  const session = await auth();
  if (!session) return Response.json({ error: 'Unauthorized' }, { status: 401 });
  
  return await updateData();
}

Defense-in-Depth Architecture

Multiple layers of security controls prevent single points of failure:

• Middleware: Global route protection
• Handler-level: Individual endpoint authentication
• Business Logic: Operation-specific authorization
• Data Layer: Database-level access controls

Common Vulnerabilities

Authentication Bypass

Risk: Server-side code importing handlers directly bypasses middleware Impact: Complete authentication bypass in certain execution contexts Solution: Implement authentication within each handler

Deprecated Framework Patterns

Problem: Relying on deprecated middleware patterns Risk: Framework updates removing support expose all routes Mitigation: Migrate to current framework authentication patterns

Weak Credential Management

Common issues include:

• Plaintext password storage in environment variables
• Lack of password hashing (bcrypt/argon2)
• No rate limiting or brute force protection
• Single shared credentials across users

Concurrent Operation Security

Locking Mechanisms

Long-running API operations require proper concurrency controls:

• Mutex/Semaphore: Prevent parallel execution
• Database Locking: Row-level or table-level locks
• Distributed Locks: Redis-based coordination
• Operation Queues: Sequential processing

State Protection

• Atomic Operations: Database transaction boundaries
• Idempotency: Safe retry mechanisms
• Conflict Detection: Optimistic concurrency control

Access Control Lists (ACL)

Role-Based Permissions

async function checkPermission(operation: string, user: User) {
  const userRole = await getUserRole(user.id);
  return hasPermission(userRole, operation);
}

export async function POST(request: Request) {
  const session = await auth();
  if (!session) return unauthorized();
  
  const hasAccess = await checkPermission('admin:reseed', session.user);
  if (!hasAccess) return forbidden();
  
  return await seedMappings();
}

Operation-Level Authorization

• Admin Operations: Mapping reseeds, system configuration
• User Operations: Data viewing, basic updates
• System Operations: Automated sync, background tasks

Best Practices

Authentication Hardening

• Strong Password Requirements: Enforce complexity and length
• Multi-Factor Authentication: Additional security layers
• Session Management: Secure token handling and expiration
• Account Lockout: Protection against brute force attacks

API Endpoint Security

• Input Validation: Sanitize and validate all inputs
• Rate Limiting: Prevent abuse and DoS attacks
• CORS Configuration: Restrict cross-origin requests
• Error Handling: Avoid information disclosure in error messages

Monitoring and Alerting

• Failed Authentication Attempts: Detect brute force attacks
• Concurrent Operation Detection: Monitor for race conditions
• Privilege Escalation Attempts: Detect unauthorized access patterns
• API Usage Patterns: Identify anomalous behavior

Production Considerations

Deployment Security

• Environment Variable Protection: Secure credential storage
• Network Segmentation: Isolate API tiers
• TLS Termination: Encrypt data in transit
• Secret Rotation: Regular credential updates

Operational Security

• Audit Logging: Comprehensive operation tracking
• Incident Response: Rapid security issue resolution
• Penetration Testing: Regular security assessments
• Compliance: Meet regulatory requirements

See also

• authentication-systems
• Authorization Patterns
• concurrent-operation-management
• Production Security