What is the primary function of a web application firewall (WAF)?

The primary function of a web application firewall (WAF) is to protect applications from web-based attacks. A WAF is designed to filter and monitor HTTP traffic between a web application and the internet, examining the data transmitted and detecting patterns associated with common web vulnerabilities. These may include attacks such as SQL injection, cross-site scripting (XSS), and other attempts to exploit application logic. By identifying and blocking potentially harmful requests before they reach the application, a WAF enhances the security posture of web applications significantly.

While blocking unauthorized access is important, it is more commonly associated with traditional firewalls or network security measures. Increasing bandwidth is not a function of a WAF, as it does not enhance network performance but rather focuses on security. Additionally, serving web content to users is fundamentally a function of web servers rather than security infrastructure. Thus, the focus of a WAF on safeguarding applications from various attack vectors makes it critical for protecting sensitive data and maintaining application integrity.