Thursday, January 27, 2011

Vanilla Forums 2.0.16 <= Cross Site Scripting Vulnerability


1. OVERVIEW
The Vanilla Forums 2.0.16 and lower versions were vulnerable to Cross
Site Scripting.

2. BACKGROUND
Vanilla Forums are open-source, standards-compliant, customizable
discussion forums.
It is specially made to help small communities grow larger through SEO
mojo, totally customizable social tools,
and great user experience. Vanilla is also built with integration at
the forefront, so it can
seamlessly integrate with your existing website, blog, or custom-built
application.

3. VULNERABILITY DESCRIPTION
The 'Target' parameter was not properly sanitized after user logs in,
which allows attacker to conduct Cross Site Scripting attack.
An attacker could prepare a link in a forum post that includes a link
to a file which seems to require authentication.
Upon logging in, user will get XSSed.

4. VERSIONS AFFECTED
2.0.16 and lower

5. PROOF-OF-CONCEPT/EXPLOIT
http://vanilla/index.php?p=/entry/signin&Target=javascript:alert(document.cookie)//http://

6. SOLUTION
Upgrade to Vanilla Forums 2.0.17 or higher

7. VENDOR
Vanilla Forums Development Team
http://vanillaforums.org/

8. CREDIT
This vulnerability was discovered by Aung Khant, http://yehg.net, YGN
Ethical Hacker Group, Myanmar.

9. DISCLOSURE TIME-LINE
2010-12-14: notified vendor
2011-01-18: vendor released fix
2011-01-27: vulnerability disclosed

10. REFERENCES
Original Advisory URL:
http://yehg.net/lab/pr0js/advisories/[vanilla_forums-2.0.16]_cross_site_scripting
What XSS Can Do: http://yehg.net/lab/pr0js/view.php/What%20XSS%20Can%20Do.pdf
XSS FAQs: http://www.cgisecurity.com/articles/xss-faq.shtml
XSS (wiki): http://en.wikipedia.org/wiki/Cross-site_scripting
XSS (owasp): http://www.owasp.org/index.php/Cross-site_Scripting_(XSS)
CWE-79
: http://cwe.mitre.org/data/definitions/79.html

#yehg [2011-01-27]
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Best regards,
YGN Ethical Hacker Group
Yangon, Myanmar
http://yehg.net
Our Lab | http://yehg.net/lab
Our Directory | http://yehg.net/hwd