Cisco's AnyConnect VPN solution provides remote access to customers via the Web browser. This is accomplished through the use of a Java applet. The applet 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 vulnerability within Cisco Systems Inc's AnyConnect VPN Java client allows attackers to execute arbitrary code with the privileges of the targeted user.
The Java applet is used to install the VPN client. Once it is instantiated, it will attempt to download two files from the site specified 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. If the control is already installed, all an attacker has to do to exploit the vulnerability is embed a link to an executable which will be downloaded and executed.
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.
iDefense is currently unaware of any workarounds for this vulnerability.
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-2011-2040 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.
08/11/2010 Initial Vendor Notification
08/12/2010 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.