Hello list!

I want to warn you about Abuse of Functionality, Insufficient
Anti-automation, XML Injection and Cross-Site Scripting vulnerabilities in
MyBB.

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Affected products:
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Vulnerable are MyBB 1.6.1 and previous versions.

In versions MyBB 1.6.2 and 1.4.15 XML Injection and XSS holes were fixed
(http://blog.mybb.com/2011/02/22/mybb-1-6-2-and-1-4-15-security-update/).

Also developers have tried to fix IAA by adding new parameter my_post_key to
request, but it'd not help against IAA. Because it's enough to take value of
this parameter from forum's page (which can be done by program) and later on
to conduct automated login enumeration attack.

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Details:
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Abuse of Functionality (WASC-42):

These functionalities allow to conduct Login Enumeration attack.

http://site/xmlhttp.php?action=username_availability&value=test

http://site/xmlhttp.php?action=username_exists&value=test

Insufficient Anti-automation (WASC-21):

These functionalities have no protection from automated attacks. Which
allows to automate login enumeration via Abuse of Functionality
vulnerabilities, to reveal logins of users in the system.

XML Injection (WASC-23):

http://site/xmlhttp.php?action=username_exists&value=%3Cxml/%3E

XSS via XML Injection (WASC-08):

http://site/xmlhttp.php?action=username_exists&value=%3Cdiv%20xmlns=%22http://www.w3.org/1999/xhtml%22%3E%3Cscript%3Ealert(document.cookie)%3C/script%3E%3C/div%3E

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Timeline:
------------

2011.02.12 - announced at my site.
2011.02.13 - informed developers.
2011.02.22 - developers fixed some of these vulnerabilities in versions MyBB
1.6.2 and 1.4.15.
2011.04.01 - disclosed at my site.

I mentioned about these vulnerabilities at my site
(http://websecurity.com.ua/4925/).

Best wishes & regards,
MustLive
Administrator of Websecurity web site
http://websecurity.com.ua