Websense Input Validation Flaw in Blocked Site Error Message Permits Cross-Site Scripting Attacks
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SecurityTracker Alert ID: 1008374
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CVE Reference: GENERIC-MAP-NOMATCH
(Links to External Site)
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Date: Dec 4 2003
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Impact: Disclosure of authentication information, Execution of arbitrary code via network, Modification of user information
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Fix Available: Yes
Exploit Included: Yes
Vendor Confirmed: Yes
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Version(s): 4.3.0 - 5.1
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Description: An input validation vulnerability was reported in Websense. A remote user can conduct cross-site scripting attacks in certain cases.
PeterT reported that when Websense blocks a particular web site, the resulting error message displayed by Websense includes the blocked
URL. The software reportedly does not validate or filter the URL to remove HTML code.
A remote user can create a specially crafted
URL that, when loaded by a target user, will cause arbitrary scripting code to be executed by the target user's browser. The code
will originate from the site running the Websense filtering software and will run in the security context of that site. As a result,
the code will be able to access the target user's cookies (including authentication cookies), if any, associated with the site,
access data recently submitted by the target user via web form to the site, or take actions on the site acting as the target user.
A
demonstration exploit URL is provided:
http://BlockedSite?<SCRIPT>alert('hello')</SCRIPT>
The vendor was reportedly notified
on Nov 29, 2003.
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Impact: A remote user can access the target user's cookies (including authentication cookies), if any, associated with the site running the
Websense software, access data recently submitted by the target user via web form to the site, or take actions on the site acting
as the target user.
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Solution: The vendor has released a patch.
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Vendor URL: www.websense.com/ (Links to External Site)
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Cause: Input validation error
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Underlying OS: Linux (Red Hat), UNIX (Solaris - SunOS), Windows (NT), Windows (2000), Windows (2003)
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Reported By: "Mr. P.Taylor" <petert@imagine-sw.com>
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Message History:
None.
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Source Message Contents
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Date: Wed, 3 Dec 2003 11:35:39 -0500
From: "Mr. P.Taylor" <petert@imagine-sw.com>
Subject: Websense Blocked Sites XSS
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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.
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