---------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------- 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. ---------------------------------------------------------------------------- Information Risk Management Plc. 22 Buckingham Gate London SW1E 6LB +44 (0)207 808 6420
