IRM 008: Citrix Metaframe XP is vulnerable to Cross Site Scripting
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IRM Security Advisory No. 008
Citrix Metaframe XP is vulnerable to Cross Site Scripting
Vulnerablity Type / Importance: XSS / Medium
Problem discovered: August 18th 2003
Vendor contacted: August 18th 2003
Advisory published: October 31st 2003
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Abstract:
The Citrix MetaFrame Access Suite is a product that enables users to access
enterprise applications and information on demand. Metaframe XP is
vulnerable to a Cross-Site Scripting attack based on the manipulation of
error messages sent to user's web browser.
Description:
During a recent penetration test IRM identified a machine running Citrix
Metaframe XP that prompted for authentication credentials. When 'random'
credentials were supplied, a page was returned displaying the following
error:
"ERROR: The credentials supplied were invalid. Please try again."
The text used to construct this error message formed part of the URL:
https://server/citrix/metaframexp/default/login.asp?NFuse_LogoutId=On&NFuse_
MessageType=Error&NFuse_Message=Thex0020credentialsx0020suppliedx0020werex00
20invalidx002ex0020x0020Pleasex0020tryx0020againx002e
If the URL was changed to the following:
https://server/citrix/metaframexp/default/login.asp?NFuse_LogoutId=On&NFuse_
MessageType=Error&NFuse_Message=<SCRIPT>alert("Vulnerable to XSS")</SCRIPT>
the server processed the HTML and executed the javascript on the user's
browser.
Citrix were contacted and immediately confirmed that this was indeed a
security issue and set about producing a patch to include in the next update
for the product.
Tested Versions:
Citrix Metaframe XP 1.0
Web Interface 2.0
Tested Operating Systems:
Microsoft Windows 2000
Vendor & Patch Information:
Citrix were contacted on August 18th 2003 and released the update on October
2nd 2003, which can be downloaded from http://www.mycitrix.com
Workarounds:
IRM are not aware of any workarounds for this issue.
Credits:
Research & Advisory: Andy Davis
Disclaimer:
All information in this advisory is provided on an 'as is'
basis in the hope that it will be useful. Information Risk Management
Plc is not responsible for any risks or occurrences caused
by the application of this information.
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Information Risk Management Plc.
22 Buckingham Gate
London
SW1E 6LB
+44 (0)207 808 6420