SYMSA-2007-006: Citrix EPA ActiveX Control Design Flaw

[research () symantec com]

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                     Symantec Vulnerability Research
                     http://www.symantec.com/research
                           Security Advisory

   Advisory ID: SYMSA-2007-006
Advisory Title: Citrix EPA ActiveX Control Design Flaw
        Author: Michael White / michael_white () symantec com
  Release Date: 19-07-2007
   Application: Citrix Access Gateway
      Platform: Internet Explorer/Win32
      Severity: Remote arbitrary code execution
 Vendor status: Patch available
    CVE Number: CVE-2007-3679
     Reference: http://www.securityfocus.com/bid/24865


Overview:

Citrix Access Gateway offers a clientless SSL VPN solution
implemented through a series of browser-based controls. As part of
the endpoint validation, the ActiveX control for Internet Explorer
downloads and executes a series of executable modules from the
remote server.

Details:

Researchers identified that the endpoint checking control can be
embedded in any web page and subverted to download and execute any
executable module of the attacker’s choosing.

This vulnerability represents a design flaw in the architecture of
the endpoint validation practice.

A high level of browser trust is required to allow the endpoint
checks to function correctly, and the control is signed by Citrix
Corporation.

Vendor Response:

This has been addressed by a product update.
See http://support.citrix.com/article/CTX113815

Recommendation:

Apply the product update as detailed in 
http://support.citrix.com/article/CTX113815

Common Vulnerabilities and Exposures (CVE) Information:

The Common Vulnerabilities and Exposures (CVE) project has assigned
the following names to these issues.  These are candidates for
inclusion in the CVE list (http://cve.mitre.org), which standardizes
names for security problems.

  CVE-2007-3679

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