Cisco Security Advisory-
Cisco Secure Desktop contains a vulnerable ActiveX control that could allow an attacker to execute arbitrary code with the privileges of the user who is currently logged into the affected system. Cisco has released a free software update that addresses this vulnerability. There is a workaround that mitigates this vulnerability.
This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20100414-csd.
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A Cisco-signed ActiveX control that is used by Cisco Secure Desktop fails to properly verify the integrity of an executable file that is used by the Cisco Secure Desktop installation process. If an attacker can entice a user to visit an attacker controlled web page, the vulnerable ActiveX control could be invoked to download an attacker-modified package. The package could contain a malicious executable file that executes with the privileges of the affected user. A successful exploit could result in a complete compromise of a vulnerable system. This vulnerability is documented in Cisco Bug ID CSCta25876 ( registered customers only) and has been assigned the Common Vulnerabilities and Exposures (CVE) ID CVE-2010-0589.
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Administrators can mitigate this vulnerability by using the kill bit feature of Microsoft Windows to prevent the loading and execution of the vulnerable ActiveX control. Administrators must use the Class identifier (CLSID) of the vulnerable ActiveX control to disable the control. The affected CLSID is:
705EC6D4-B138-4079-A307-EF13E4889A82
Instructions for setting the kill bit in Microsoft Windows are available at the following link:
http://support.microsoft.com/kb/240797
Note: Kill bit settings are permanent. The settings must be removed to regain Cisco Secure Desktop functionality. After an administrator has updated the Cisco Secure Desktop software to a fixed version on VPN portal devices, the kill bit must be removed from Microsoft Windows clients in order to allow the Cisco Secure Desktop software to be upgraded. Once the kill bit is removed, clients may be vulnerable until a fixed Cisco Secure Desktop version is installed.
Update: Cisco Secure Desktop software version 3.5.1077 replaces the old, vulnerable ActiveX CLSID with a newly issued CLSID. New installations and upgrading from an older version of Cisco Secure Desktop will use the new CLSID. Once the software upgrade has been installed on client systems, administrators can safely and permanently implement the ActiveX kill bit workaround for the old CLSID in their environment.
Additional mitigation techniques that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory:
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When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.
In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center (TAC) or your contracted maintenance provider for assistance.
Cisco Secure Desktop version 3.5.841 can be downloaded at the following link:
Note: Cisco Secure Desktop versions 3.0 and 3.1 are only supported for operation with certain versions of Cisco IOS software and Cisco Adaptive Security Appliance (ASA) software version 7.x. Cisco Secure Desktop versions 3.2 through 3.5 are only supported for operation with Cisco ASA software version 8.x. Customers running Cisco Secure Desktop versions 3.2 through 3.5 with a supported Cisco ASA software version are encouraged to upgrade to Cisco Secure Desktop version 3.5.841.
Customers with active software licenses for Cisco Secure Desktop versions 3.0 and 3.1 should send email to the following address for instructions on migrating to non-vulnerable software:
csd-activex-inquiry@cisco.com
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.
This vulnerability was discovered and reported to Cisco by an anonymous researcher working with TippingPoint's Zero Day Initiative. Cisco would like to thank TippingPoint for reporting this vulnerability and collaborating on a coordinated disclosure.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Revision 1.1
2010-July-13
Updated workarounds.
Revision 1.0
2010-April-14
Initial public release.
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