Additional technical information to describe the Cisco AnyConnect Secure Mobility Client WebLaunch input processing arbitrary code execution vulnerability is available.
Cisco AnyConnect Secure Mobility Client contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system.
The vulnerability is due to insufficient validation of input by the Cisco AnyConnect Secure Mobility Client WebLaunch component. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious website. If successful, the attacker could execute arbitrary code on the system.
Cisco confirmed the vulnerability in a security advisory and released software updates.
Cisco AnyConnect Secure Mobility Client versions prior to 2.5 MR6 and 3.0 MR8 are vulnerable.
To exploit the vulnerability, the attacker may provide a link that directs a user to a malicious site and use misleading language or instructions to persuade the user to follow the provided link.
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code on a targeted system with the privileges of a targeted user. If the user holds elevated privileges, the attacker could completely compromise the system.
The vulnerability is due to insufficient signature checks that are performed by the Cisco AnyConnect VPN Client. When the affected software is invoked through the ActiveX control, the Cisco AnyConnect VPN Client downloads and verifies that vpndownloader.exe has been signed by Cisco. The Cisco AnyConnect VPN Client then runs and downloads additional configuration files that are used to download executable files. These executable files are not checked for valid certificates and automatically run after downloading on the system.
An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to visit a malicious web page. When visited, the web page could download crafted executable files, which run on the user's system as soon as the download completes, triggering the execution of arbitrary code on the targeted system.
Administrators are advised to apply the appropriate updates.
Users are advised not to open e-mail messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in e-mail messages are safe, they are advised not to open them.
Administrators are advised to monitor affected systems.
The Cisco Applied Intelligence team has created the following companion document to guide administrators in identifying and mitigating attempts to exploit this vulnerability prior to applying updated software: cisco-amb-20120620-ac
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at firstname.lastname@example.org.
Version 1, June 20, 2012, 1:17 PM: Cisco AnyConnect Secure Mobility Client contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system. Updates are available.
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