Additional technical information for the Cisco AnyConnect Secure Mobility Client software downgrade vulnerability is publicly available.
Cisco AnyConnect Secure Mobility Client contains a vulnerability that could allow an unauthenticated, remote attacker to replace software components.
The vulnerability is due to improper sanitization of user-supplied input by the affected software's download feature. An unauthenticated, remote attacker could exploit this vulnerability by persuading a user to view a malicious website. If successful, the attacker could cause the affected software to download and install an older version of the software.
Cisco has 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 replace software components with an older version, affecting application functionality or introducing additional vulnerabilities.
The vulnerability exists in the vpndownloader.exe implementation in the WebLaunch feature of the affected software. The software fails to verify the version number of the vpndownloader.exe program it downloads.
An unauthenticated, remote attacker could exploit this vulnerability by persuading a user to view a malicious website. Processing input supplied by the malicious website could cause the software to download and install an older, signed version of the affected software. The vulnerability can be exploited by using either an ActiveX or a Java component that could offer signed code to match an older version of the software. The installation of an older version of the software could invalidate current configurations, change functionality, and introduce vulnerabilities that may be present in older versions of the software.
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 email@example.com.
Version 1, June 20, 2012, 1:16 PM: Cisco AnyConnect Secure Mobility Client contains a vulnerability that could allow an unauthenticated, remote attacker to replace software components. Updates are available.
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