[gentoo-dev] phpBB

[Sergio Jimenez Romero <TripleDES@eSlack.org>]

I'm watching at forums.gentoo.org, and see that you are using phpBB 2.0.0, and a few days ago in bugtraq there was an advisory about this forum.

Advisory:

From: Martijn Boerwinkel <xim@xs4all.nl>
To: bugtraq@securityfocus.com
Subject: Cross Site Scripting Vulnerability in phpBB2's [IMG] tag and remote avatar
Date: 26 May 2002 17:59:33 +0200
X-Mailer: Ximian Evolution 1.0.5 

phpBB2 Cross Site Scripting Vulnerability 
-------------------------------------------- 

Affected Program: phpBB2 version 2.0.0 
  (possibly earlier versions too, but not tested) 
Vendor: http://www.phpbb.com 
Vendor Status: informed on 24/04/2002, fixed issued on 20/05/2002 
Discovery Date: 24/04/2002 
Release Date: 26/05/2002 
Vulnerability Class: Cross Site Scripting 


Severity 
-------- 
Malicious users can steal other user's and admin's cookies, allowing
them to impersonate other users on the board and access to the
administration panel. 

Problem 
------- 
The problem is very similar to SQL injection. 
phpBB2 uses a user provided string (through the [IMG] tag) 
in the following HTML tag: 

<img src="$user_provided" border="0" /> 

While there is a check to force the string to begin with "http://" it
doesn't disallow ". That means a malicious user can escape the src="" in
the HTML tag and insert his own html code. 
This same problem also exists in the remote avatar part of the user
profile. 


Example 
------- 
Enter the following anywhere in a message: 

[img]http://a.a/a"onerror="javascript:alert(document.cookie)[/img] 

When reading that message it should popup an alert box with your
cookies. 

Solutions 
--------- 
* Upgrade to 2.0.1 

-- 
XiM 
(#icerealm on irc.icerealm.net) 

-----------------------------

Well, if you didn't know, now you know...hehe, sorry about my english :-)

best regards.

-- 
When tux flies, Chuck will die...

TripleDES <TripleDES@eSlack.org> - http://bsdsite.no-ip.org