Cross Site Scripting vulnerability in miniBB 1.7 (latest) and earlier

[Chintan Trivedi <chesschintan () hotmail com>]

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Advisory by Eye On Security Research Group - India www.eos-india.net 
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1...............................................................Product
2................................................................Vendor
3.........................................................Vulnerability
4.........................................................About Product
5..............................................Details of vulnerability
6...............................................................Exploit
7..............................................................Solution
8...............................................................Credits




1. Product 
==========

miniBB 1.7 (latest) and earlier


2. Vendor
=========

www.minibb.net


3. Vulnerability
================

Cross Site Scripting vulnerability in bb_func_usernfo.php


4. About miniBB
===============

(direct quote from www.minibb.net)

        miniBB ("minimalistic bulletin board") is flat linear (non-tree) version of highly customizable bulletin board. 
It inherits most popular features from the bulletin boards the planet has at this moment, with one exception: it is 
very small by size (2-5 times smaller than usual boards), very fast and FREE. Mostly miniBB is designed for small and 
medium Internet-sites, but also can be used in large projects. 


5. Details of vulnerability
===========================

        bb_func_usernfo.php contains code to take data from "minibb_users" table and display information about a 
particular user requested. The code for displaying website of the any user in bb_func_usernfo.php is as follow :

if ($row[6]!='') $row[6]='<a href="'.$row[6].'" target="_blank">'.$row[6].'</a>'; else $row[6]='';

So an attacker can create a login in the forums and in the preferences, give his website name as 
http://blah.com";></a>&lt;script&gt;somejavascriptcode&lt;/script&gt;

Hence when others will try to view his profile, the inserted javascript code will be executed. The actual bug lies in 
the "bb_edit_prf.php" file where the website name inserted by a user in his preferences is not validated properly.  

6. Exploit
==========

        Create a user in the forums with your website name as 
http://blah.com";></a>&lt;script&gt;alert(document.cookie)&lt;/script&gt;
Now suppose your userid is 5, then just clicking http://[target]/index.php?action=userinfo&user=5 will execute the 
script. 

7. Solution
===========

        Check for the validation of the user data while editing his preferences in the "bb_edit_prf.php" file and 
filter out strings like "&lt;script&gt;", quotes, "cookie" etc.


8. Credits
==========

Chintan Trivedi - http://www.hackersprogrammers.com
"Eye on Security Research Group - India " - www.eos-india.net