API Security Best Practices
Essential strategies for securing your REST and GraphQL APIs against common attacks
APIs are the backbone of modern web applications, enabling communication between services and powering mobile apps, single-page applications, and microservices architectures. However, they also present a significant attack surface if not properly secured. This guide covers essential best practices for API security.
Authentication and Authorization
Never rely on API keys alone for authentication. Implement OAuth 2.0 or JWT (JSON Web Tokens) for proper authentication and authorization. Always validate tokens on the server side and implement proper token expiration and refresh mechanisms.
Best Practices:
- Use OAuth 2.0 for third-party integrations
- Implement JWT with short expiration times
- Always use HTTPS to prevent token interception
- Implement proper refresh token rotation
Rate Limiting and Throttling
Implement rate limiting to prevent abuse, brute force attacks, and denial of service. Rate limits should be applied per user, per IP address, and globally. Consider implementing different rate limits for authenticated vs. unauthenticated requests.
Example: Limit authenticated users to 1000 requests per hour, unauthenticated users to 100 requests per hour, and implement sliding window rate limiting for better accuracy.
Input Validation and Sanitization
Never trust client input. Implement strict input validation on all API endpoints. Validate data types, formats, ranges, and lengths. Use allowlists rather than denylists when possible. Sanitize input to prevent injection attacks.
Validation Checklist:
- Validate data types (string, number, boolean)
- Check string lengths and ranges
- Use regex for format validation (email, phone, etc.)
- Implement schema validation (JSON Schema, Yup, Zod)
- Reject unexpected fields
Secure Data Transmission
Always use HTTPS/TLS for API communication. Never transmit sensitive data in URL parameters where it can be logged in server logs, browser history, and proxy logs. Use POST requests with encrypted payloads for sensitive operations.
Error Handling
Implement proper error handling that doesn't leak sensitive information. Generic error messages should be returned to clients while detailed errors are logged server-side. Never expose stack traces, database errors, or internal system information in API responses.
Bad: "SQL Error: Table 'users' doesn't exist at line 42"
Good: "An error occurred processing your request. Reference ID: 12345"
API Versioning and Deprecation
Implement proper API versioning to allow for security updates without breaking existing integrations. Clearly communicate deprecation timelines and security fixes. Consider using header-based versioning rather than URL-based for cleaner API design.
Monitoring and Logging
Implement comprehensive logging of all API requests, authentication attempts, and security events. Monitor for unusual patterns such as sudden spikes in failed authentication, access to sensitive endpoints, or unusual request patterns. Use SIEM tools for real-time security monitoring.
Conclusion
API security is not a one-time implementation but an ongoing process. Regular security audits, penetration testing, and staying updated with the latest security best practices are essential. Consider implementing an API gateway for centralized security policy enforcement.
Need help securing your APIs? All Web Security offers comprehensive API security assessments and penetration testing services. Contact us at info@allwebsecurity.online to learn more.