October 31, 2021
In October 2021 the Belgian ethical hacking platform Intigriti hosted a new XSS (cross site scripting) challenge.
The challenge was build around mutation XSS (mXSS) were a HTML injection could be exploited. The browser tries to fix our malformed injected HTML tags and thus "mutates" the HTML source code. This combined with some weak spots in the CSP policy allows the execution of a XSS attack against the webpage.
Embedded writeup PDF: