Web application firewall

Why it matters

It is a layer of defence that catches known, common attack patterns without requiring the application code itself to defend against every one individually, which matters because new attack variations appear constantly and an application cannot be rewritten instantly every time one does. It also buys time: when a new vulnerability class is disclosed publicly, a WAF rule can often be deployed within hours to block the specific attack pattern, well before every affected application can be patched at the code level. It also benefits from being paired with rate limiting and bot detection, since a WAF alone does not address high-volume automated abuse that does not match a specific known attack signature.

What goes wrong when it's handled badly

Relying on a WAF as the only defence, rather than one layer among several, is a common mistake: a WAF blocks known patterns, not application logic flaws or a vulnerability nobody has seen exploited yet. A WAF configured too permissively to avoid blocking legitimate traffic can end up providing far less real protection than its presence implies. A concrete example is a WAF blocking a legitimate customer's search query because it happened to contain a word pattern resembling a SQL injection attempt, a false positive that, without careful tuning, quietly turns real customers away rather than attackers. Reviewing WAF logs periodically for both blocked attacks and false positives, rather than treating it as fire-and-forget once configured, is what keeps it tuned correctly as traffic patterns change. Keeping WAF rules updated against newly disclosed attack patterns, not just the set configured at initial setup, is what keeps it genuinely current rather than a static snapshot.