--------------------- SUMMARY ---------------------
Name:
XennoBB "avatar gallery" directory transversal (10/8/2006)
Vendor / Product:
XennoBB Group
http://www.xennobb.com/
Description:
The world's most revolutionary and easy to use bulletin board.
Revolutionary because it redefines the boundaries of usability
and power; from the first version it's a real alternative to
the commercial forums out there.
How can XennoBB be described in few words?
Lightning-speed, stable, SECURED(?) and modern.
Version(s) Affected:
<= 2.1.0
Severity:
Medium
Impact:
Directory transversal (Remote)
Status:
Unpatched
Discovered by:
Chris Boulton <http://www.surfionline.com>
Original advisory:
http://www.surfionline.com/security_advisories/20060810_xennobb_avatar_g
allery_transversal.txt
------------------- DESCRIPTION -------------------
An exploit exists in the above mentioned versions of XennoBB which
can be exploited by malicious users to transverse various directories
on the server.
Input passed to the "gallery" parameter in profile.php is not properly
sanitized before being used to open the corresponding directory on the
file system. This exploit can lead to manipulation of content in higher
up directories than the script intends.
--------------------- EXPLOIT ---------------------
Submit a forged POST request to
profile.php?action=avatar_gallery&id={your registered user ID here}
With the following as the POST data:
category=../../general/
Successful exploitation leads to images in the /img/general folder
being shown to the user. A similar process can be used to obtain other
confidential system documents or images which may exist on the server.
--------------------- SOLUTION --------------------
Ensure input is correctly sanitized and invalid/not acceptable
characters are removed from the gallery POST variable before the
directory is opened on the server.
