Course

In this lab, titled XSS 06, part of the essential badge, you will learn to exploit an XSS vulnerability where the injection point is already within a script tag. Unlike previous challenges where you might inject directly into HTML, this time you need to carefully add your JavaScript payload within the existing code structure. This requires a nuanced approach, as you must ensure that your injected code not only executes but also does not break the pre-existing JavaScript.

To succeed, you must first analyze the HTML source of the page to identify the precise injection point. Next, rather than using a script tag, you will complete the existing JavaScript syntax with your payload. This involves appending your code and possibly terminating the unwanted code that follows your injection point, either by commenting it out or inserting dummy code. Once you manage to trigger an alert box with your UUID, you can submit the payload to the main website and verify the challenge completion by observing the alert in the victim's browser.