A Web Application Firewall (WAF) is a security tool designed to protect web applications from various types of cyberattacks and malicious activity, particularly those that target vulnerabilities in the application layer. It acts as a filter between the web server and the user, analyzing incoming traffic to detect and block harmful requests before they reach the application. WAFs are specifically designed to safeguard against common web application threats like SQL injection, cross-site scripting (XSS), cross-site request forgery (CSRF), and denial-of-service (DoS) attacks.
WAFs work by examining the HTTP/HTTPS traffic sent to and from the web application, looking for patterns that match known attack vectors or behaviors. When suspicious traffic is detected, the WAF can block, log, or alert administrators about the potentially harmful request. Many WAFs are customizable, allowing businesses to define security policies and filtering rules specific to their web application. By sitting between the user and the application, a WAF helps protect sensitive data, prevent breaches, and ensure the availability and integrity of web applications.