FirstBlood-#430 — Reflective xss on register.php with user interaction
This issue was discovered on FirstBlood v2
On 2021-10-25, shivam18u Level 3 reported:
I found a reflective XSS which can be triggered with user interaction.
By visiting the link
https://20380f62fd41-shivam18u.a.firstbloodhackers.com/register.php?ref=ja%0Avasc%0Aript:alert(document.domain)and clicking on
Return to previous page, the xss can be triggered.
You can see the link in the bottom left corner after hovering the mouse on
Return to previous pagebutton
The hacker can use social engineering to make the victim click on the
Return to previous pagebutton.
Have a nice day!
FirstBlood ID: 32
Vulnerability Type: Reflective XSS
The parameter ?ref on register.php was poorly fixed and can be bypassed in various ways. Firstly the developer failed to use strtolower() when comparing strings, and the use of characters such as
%09 will also bypass the filter.