This website uses cookies to distinguish you from other users of our website. The use of cookies helps us to provide you with a specific service, to facilitate website use, to understand our visitors and to advertise to you. By continuing to browse the site you are giving consent to our use of cookies. Learn more in our Privacy Statement.

Security Services

Cisco AnyConnect VPN Client Arbitrary Program Execution Vulnerability



Cisco's AnyConnect VPN solution provides remote access to customers via the Web browser. This is accomplished through the use of an ActiveX control. The control itself is provided by the server upon connecting. Cisco states that AnyConnect VPN supports all Adaptive Security Appliance (ASA) models. For more information, visit the following URL.


Remote exploitation of a design error within Cisco Systems Inc's AnyConnect VPN client allows attackers to execute arbitrary code with the privileges of a user running Internet Explorer.

The vulnerability exists within the ActiveX control with the following identifiers:

 CLSID: 55963676-2F5E-4BAF-AC28-CF26AA587566 ProgId: Cisco.AnyConnect.VPNWeb.1 File: %WINDIR%system32vpnweb.ocx 

This ActiveX control is not marked as safe for initialization or scripting within the registry, but it does implement IObjectSafety. When queried, this control's IObjectSafety interface reports that it is safe for both scripting and initialization.

This ActiveX control is used to install the VPN client. Once it is instantiated, it will attempt to download two files from the site supported in the "url" property. As such, an attacker can craft a page such that the control will download an executable of their choosing.

One of the files will be executed upon the successful completion of the download. This allows an attacker to execute an arbitrary executable on the user's system.


Exploitation allows attackers to execute arbitrary code in the context of the currently logged-on user. To exploit this vulnerability, a targeted user must load a malicious Web page created by an attacker. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites.

Additionally, in a default configuration, a targeted user must have this control already installed or must accept several warning prompts at the time that the attack is taking place. This control is not on the white list included with Internet Explorer 7.0. More information can be found at the following URL.


Cisco AnyConnect VPN client versions prior to 2.3.185 for Windows, 2.5.3041 and 3.0.629 for Linux and Apple Mac OS X are vulnerable.


Setting the kill-bit for this control will prevent it from being loaded within Internet Explorer. However, doing so will prevent legitimate use of the control.


Cisco has released an advisory which describes methods of updating the AnyConnect Secure Mobility Client. For more information, consult their advisory at the following URL.


The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2011-2039 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


02/24/2009 Initial Vendor Notification
02/25/2009 Initial Vendor Reply
06/01/2011 Coordinated Public Disclosure


This vulnerability was reported to iDefense by Elazar Broad.

Get paid for vulnerability research

Free tools, research and upcoming events


Copyright © 2011 Verisign, Inc.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customer service for permission.

Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.