my little forum XSS

my little forum Cross-site scripting
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Product: my little forum
Version: 2.0 (beta 23), 1.75
Vendor: http://mylittleforum.net/
Date: 02/11/08

- Introduction

"my little forum is a simple PHP and MySQL based web-forum that displays
the messages in classical threaded view."

- Details

my little forum contains a flaw that allows a remote persistent cross site
scripting attack. The application does not validate [img] BBCode tags when
a user submits a forum post. This could be used to post javascript code
to the forum. IE6 and below will execute scripts stored in the src attribute
of an image element. IE7 and FireFox are not vulnerable.

- Proof of Concept

[img]javascript:alert(document.cookie)[/img]
which is converted to
<img src="javascript:alert(document.cookie)" alt="[image]" />

- Solution

Author was notified of security issue (2/4). Upgrade to 2.0 beta 24 or
disable the ability to use the [img] BBCode tag in your forum.

Author: dB
Email: dB [at] rawsecurity.org
Received on Feb 12 2008