Web Application Firewall Rules: Protecting Against OWASP Top 10 in 2026
A WAF is your last line of defense before malicious requests reach your application. Properly configured rules block the majority of automated attacks.
SQL Injection Protection
Block requests containing SQL keywords in unexpected places. But avoid false positives — a blog post about SQL should not trigger the WAF. Use context-aware rules that only inspect query parameters and form bodies, not request paths or content bodies for content management systems.
Server-Side Request Forgery (SSRF)
SSRF moved to OWASP Top 3 because cloud metadata endpoints make it devastating. Block requests to internal IP ranges (169.254.169.254, 10.0.0.0/8, 172.16.0.0/12) at the WAF level. This protects even if application code has an SSRF vulnerability.
Rate Limiting Patterns
Global rate limits are too blunt. Implement tiered limits: 100 req/min for unauthenticated users, 1000 req/min for authenticated, 10 req/min for login endpoints. Use sliding windows, not fixed windows, to prevent burst attacks at window boundaries.
Bot Detection
Challenge suspicious patterns: rapid sequential requests, missing browser fingerprint, unusual User-Agent strings. Use JavaScript challenges (not CAPTCHAs) that legitimate browsers solve transparently.