This tweet describes a reflected cross-site scripting (XSS) vulnerability exploit through an open redirect parameter (u) which is used to execute javascript code. The user attempted to bypass the web application firewall (WAF) that blocks the normal alert(1) JavaScript function payload by using an alternative payload alert'1'. The WAF filters the common alert(1) call but fails to block this specific variation, allowing the reflected XSS to successfully execute. The tweet implies that the author discovered this bypass two months prior and shares it as a bug bounty tip, hoping to get acknowledged before any major consequences (WW3, metaphorically). The technique involves using open redirect parameters to load malicious JavaScript code and using slight variations in payload encoding or syntax to bypass WAF string matching filters.
For more insights, check out the original tweet here: https://twitter.com/0xSekiro/status/1937277209649250688. And don’t forget to follow @0xSekiro for more exciting updates in the world of cybersecurity.