Vendor  : Phorum
URL     : http://www.phorum.org
Version : Phorum 5.0.3 Beta && Earlier
Risk    : Cross Site Scripting



Description:
Phorum is a web based message board written in PHP. Phorum is designed 
with high-availability and visitor ease of use in mind. Features such as 
mailing list integration, easy customization and simple installation make 
Phorum a powerful add-in to any website.



Problem:
Phorum have patched a good number of XSS (Cross Site Scripting) issues in 
the past, but there is still some work to be done regarding these issues 
before the final release of Phorum Version 5. The first issue I am going 
to talk about lies in "login.php" If you look at the HTML source code you 
should see two hidden variables. One called "f" which specifies the forum 
id, and one called "target" which specifies the location to take the user 
after they login. Unfortunately both of these values are taken directly 
from the value of HTTP_REFERER without any validation. While there is a 
global script in forum that checks for the <script> tag, it will allow for 
pretty much any thing else, and most of you know it is not hard to execute 
javascript inside of a tag which is allowed. This same vulnerability also 
exists in "register.php" And while not the exact same, a similar problem 
to these two exists in "profile.php" also. Below are some examples.

login.php?HTTP_REFERER=[XSS]
register.php?&HTTP_REFERER=[XSS]
profile.php?id=2&action=edit&target=[XSS]



Solution:
The vendor was contacted and immediately responded, and will be releasing a 
fix soon. Thanks to Brian Moon and the rest of the forum dev team for such a 
quick response. It is appreciated. The original advisory can be located at
the following location http://www.gulftech.org/03152004.php



Credits:
Credits go to JeiAr of the GulfTech Security Research Team. 
http://www.gulftech.org