TITLE:
YaBB Cross-Site Scripting and Security Bypass Vulnerabilities

SECUNIA ADVISORY ID:
SA12593

VERIFY ADVISORY:
http://secunia.com/advisories/12593/

CRITICAL:
Moderately critical

IMPACT:
Security Bypass, Cross Site Scripting

WHERE:
>From remote

SOFTWARE:
YaBB 1.x
http://secunia.com/product/541/

DESCRIPTION:
GulfTech Security has discovered two vulnerabilities in YaBB, which
can be exploited by malicious people to conduct cross-site scripting
attacks and bypass certain security restrictions.

1) Input passed to the "board" parameter in "YaBB.pl" is not properly
sanitised before being returned to the user. This can be exploited to
execute arbitrary script code in a user's browser session in context
of a vulnerable site.

Example:
http://[victim]/YaBB.pl?board=;action=imsend;to=[code]

2) Some administrative actions are performed just by accessing an
URL. This can e.g. be exploited by malicious users by posting a
message containing an image, which refers to an URL used for
performing an administrative task, in a forum.

Successful exploitation invokes the action automatically when the
administrator reads the forum posting.

Example (remove board):
http://[victim]/YaBB.pl?board=;action=modifycat;id=[cateogoryname];moda=Remove2

The vulnerabilities have been confirmed on YaBB 1 GOLD SP 1.3.2.
Other versions may also be affected.

SOLUTION:
Edit the source code to ensure that input is properly sanitised.

PROVIDED AND/OR DISCOVERED BY:
GulfTech Security

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