XSS Web Application Firewall Bypass Techniques

Introduction

Cross-Site Scripting (XSS) is one of the most common vulnerabilities found in web applications. It occurs when an attacker injects malicious scripts into a web application, which are then executed in the context of another user’s session. Web Application Firewalls (WAFs) are commonly used to protect web applications from such attacks by filtering and monitoring HTTP traffic. However, WAFs are not foolproof, and skilled attackers can sometimes find ways to bypass these protections.

In this comprehensive blog post, we will delve into various techniques used to bypass WAFs to exploit XSS vulnerabilities. We’ll cover the basics of XSS, how WAFs attempt to mitigate it, and the methods used by attackers to evade these protections. Please note that this information is provided strictly for educational purposes and should not be used for any illegal activities.

Understanding XSS

What is XSS?

Cross-Site Scripting (XSS) is a security vulnerability that allows an attacker to inject malicious scripts into a web application. These scripts are then executed in the user’s browser, leading to various malicious outcomes such as:

• Stealing Cookies: An attacker can steal session cookies and impersonate the user.
• Phishing: The attacker can redirect users to a malicious site or create a fake login page.
• Keylogging: Scripts can be used…