Web Application Firewall (WAF)
Definition
A Web Application Firewall (WAF) is a specific type of firewall that helps protect web applications by filtering and monitoring HTTP traffic between a web application and the Internet. It typically protects web applications from attacks such as cross-site scripting (XSS), SQL injection, and path traversal.
Why It Matters
A WAF acts as a shield specifically for web applications, sitting in front of them to block common web-based attacks before they can reach the application itself. It provides an important layer of defense against many known vulnerabilities.
Contextual Example
An e-commerce site places a WAF in front of its web servers. The WAF is configured with rules to automatically block requests that look like SQL injection or cross-site scripting attacks, protecting the underlying application code from these threats.
Common Misunderstandings
- A WAF operates at the application layer (Layer 7), whereas a traditional network firewall typically operates at the network and transport layers (Layers 3 and 4).
- WAFs are a critical security control for any public-facing web application.