API security best practices: protecting endpoints from common attacks

APIs are the primary attack surface for modern applications. Every endpoint you expose is a potential entry point for attackers. Securing your API requires a defense-in-depth approach that addresses multiple attack vectors.

Authentication verifies who the user is. Use a standard protocol like OAuth 2.0 or JWT-based authentication. Never roll your own authentication. Validate tokens on every request, check expiration, and enforce proper signature verification.

Authorization verifies what the user can do. Implement authorization at the API layer, not just the UI. Every endpoint should independently check that the authenticated user has permission to perform the requested action. Use a consistent authorization pattern.

Input validation is your first defense against injection attacks. Validate and sanitize all user input query parameters, request bodies, headers, and file uploads. Use parameterized queries for database access to prevent SQL injection. Use a validation library that enforces strict typing.

Rate limiting prevents abuse and denial of service. Implement rate limiting per user and per IP address. Use the token bucket or sliding window algorithm. Return appropriate 429 responses with Retry-After headers.

CORS configuration must be precise. Don't use wildcard origins in production. Specify exactly which origins are allowed, which methods they can use, and which headers they can send. Handle preflight OPTIONS requests correctly.

HTTPS is non-negotiable. Enforce HTTPS for all API endpoints. Use HSTS headers to tell browsers to always use HTTPS. Redirect HTTP to HTTPS. Disable weak TLS versions and cipher suites.

Log and monitor API access. Log all authentication attempts, authorization failures, and unusual request patterns. Use a WAF to detect and block common attack patterns. Monitor for suspicious activity and alert on potential security incidents.

-

Rizwan Saleem | https://rizwansaleem.co