Web Application Penetration Testing

The Art of Identifying X$$ & WAF Bypass Fuzzing Technique

A smart way to hunt Cross-Site Scripting vulnerability

3 min readSep 30, 2023



Cross-site scripting (XSS) vulnerabilities are among the most common security issues in web applications today. Exploiting an XSS vulnerability allows an attacker to inject malicious scripts into a trusted website, potentially compromising user data, session cookies, and even the entire application. To effectively hunt for XSS vulnerabilities, you need a systematic approach, especially when dealing with Web Application Firewalls (WAFs). In this article, we’ll explore the art of hunting XSS vulnerabilities and discuss techniques for bypassing WAFs.

1. Detect the WAF

Before you start hunting for XSS vulnerabilities, it’s crucial to confirm if the target application is behind a Web Application Firewall (WAF). WAFs are security systems that filter and monitor incoming web traffic, designed to protect web applications from various attacks, including XSS. In order to begin your hunting process, it’s important first to determine whether or not a WAF is present.

wafw00f usage WAF detect

2. Use Basic HTML Injection Payloads