vBulletin 4.0.8 PL1 XSS Filter Bypass within Profile Customization



EDB-ID: 15590 CVE: N/A OSVDB-ID: N/A
Author: MaXe Published: 2010-11-20 Verified: Verified
Exploit Code:   Download Vulnerable App:   N/A

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# Exploit Title: vBulletin 4.0.8 PL1 - XSS Filter Bypass within Profile
Customization
# Google Dork: "Powered by vBulletin Version 4.0.8" -"vBulletin.com is
now powered by"
# Date: 20th November 2010
# Author: MaXe
# Software Link: Commercial software.
# Version: 4.0.8 PL1
# Screenshot: See attachment.
# Tested on: Windows and Linux (Server) + IE6 (Client).


vBulletin - XSS Filter Bypass within Profile Customization


Versions Affected: 4.0.8 PL1 (3.8.* is not vulnerable.)

Info:
Content publishing, search, security, and more - vBulletin has it all.
Whether it's available features, support, or ease-of-use, vBulletin offers
the most for your money. Learn more about what makes vBulletin the
choice for people who are serious about creating thriving online
communities.

External Links:
http://www.vbulletin.com

Credits: MaXe (@InterN0T)


-:: The Advisory ::-
vBulletin is prone to a Persistent Cross Site Scripting vulnerability
within the
Profile Customization feature. If this feature is not enabled the
vulnerability
does not exist and the installation of vBulletin is thereby secure.

Within the profile customization fields, it is possible to enter colour
codes,
rgb codes and even images. The image url() function does not sanitize user
input in a sufficient way causing vBulletin to be vulnerable to XSS attacks.

With the previous patch for vBulletin 4.0.8 PL1, most attacks were disabled
however it is possible to bypass this filter and inject data which is
then executed
effectively against though not limited to Internet Explorer 6.

Proof of Concept:
url(vbscript:msgbox("X/SS"))


-:: Solution ::-
Update vBulletin to version: 4.0.8 PL2


Disclosure Information:
- Vulnerability found and researched: 18th November 2010
- Disclosed to vendor (Internet Brands): 18th November
- Patch from Vendor available: 19th November
- Disclosed at: InterN0T, Full Disclosure, Bugtraq and Exploit: 20th
November


References:
http://forum.intern0t.net/intern0t-advisories/3398-vbulletin-4-0-8-pl1-cross-site-scripting-filter-bypass-within-profile-customization.html
http://forum.intern0t.net/intern0t-advisories/3349-vbulletin-4-0-8-persistent-cross-site-scripting-via-profile-customization.html