Websense Blocked Sites XSS

["Mr. P.Taylor" <petert () imagine-sw com>]

Websense Blocked Sites XSS

Risk: High

Product: Websense Enterprise v4.3.0 - v5.1 (Maybe others we only
tested this version)

Product URL: http://www.websense.com

Found By: PeterT - petert () imagine-sw com

Problem:
When Websense blocks a web site, it returns a web page to the browser
stating
that the site has been blocked. This error message contains the URL which
was
requested. Websense does not do any validation or encoding of the URL before
returning it in the error message. This allows an attacker to supply a URL
that
contains script <JavaScript, ActiveX, VB). This script will run in the
context
of a server in the trusted domain and combined with other IE flaws can have
serious consequences.

We have marked this as a High risk because we believe that allowing
attackers
to run arbitrary programs on your desktop at will, is a serious problem.


Proof of Concept:
A URL like
http://BlockedSite?<SCRIPT>alert('hello')</SCRIPT> will run script.

Resolution:
The vendor has come out with a patch. Notified on Nov 29, 2003.

Thanks to Websense for fixing this issue.

Disclaimer:
Standard disclaimer applies. The opinions expressed in this advisory are
our own and not of any company. The information within this advisory may
change without notice. Use of this information constitutes acceptance for
use in an AS IS condition. There are no warranties with regard to this
information. In no event shall the author be liable for any damages
whatsoever arising out of or in connection with the use or spread of this
information. Any use of this information is at the user's own risk.