Web Application Firewall (WAF)
What is Web Application Firewall (WAF)?
Web Application Firewall (WAF)A reverse-proxy filter that inspects HTTP/HTTPS traffic to block web attacks such as SQL injection, XSS, and bot abuse before they reach the application.
A Web Application Firewall (WAF) sits in front of a web application — usually as a reverse proxy, sidecar, or CDN edge service — and analyses each HTTP request and response against rule sets such as the OWASP Core Rule Set. It can block injection attempts, malicious file uploads, scanner traffic, layer-7 DDoS, credential stuffing, and bot abuse, often using a mix of signatures, anomaly scoring, rate limiting, and machine-learning models. WAFs are essential for protecting legacy or third-party apps that cannot be patched quickly. They must be tuned to reduce false positives, run in detection mode before blocking, and be combined with secure coding rather than treated as a substitute for it.
● Examples
- 01
AWS WAF blocking a request containing a UNION SELECT payload before it reaches the application.
- 02
Cloudflare WAF rate-limiting login endpoints to mitigate credential stuffing.
● Frequently asked questions
What is Web Application Firewall (WAF)?
A reverse-proxy filter that inspects HTTP/HTTPS traffic to block web attacks such as SQL injection, XSS, and bot abuse before they reach the application. It belongs to the Network Security category of cybersecurity.
What does Web Application Firewall (WAF) mean?
A reverse-proxy filter that inspects HTTP/HTTPS traffic to block web attacks such as SQL injection, XSS, and bot abuse before they reach the application.
How do you defend against Web Application Firewall (WAF)?
Defences for Web Application Firewall (WAF) typically combine technical controls and operational practices, as detailed in the full definition above.
What are other names for Web Application Firewall (WAF)?
Common alternative names include: WAF.