ZDI-11-091: (0day) Cisco Secure Desktop CSDWebInstaller Remote Code Execution Vulnerability

http://www.zerodayinitiative.com/advisories/ZDI-11-091

February 23, 2011

-- CVE ID:
CVE-2011-0926

-- CVSS:
9, (AV:N/AC:L/Au:N/C:P/I:P/A:C)

-- Affected Vendors:
Cisco

-- Affected Products:
Cisco Secure Desktop

-- TippingPoint(TM) IPS Customer Protection:
TippingPoint IPS customers have been protected against this
vulnerability by Digital Vaccine protection filter ID 8247. 
For further product information on the TippingPoint IPS, visit:

    http://www.tippingpoint.com

-- Vulnerability Details:
This vulnerability allows remote attackers to execute arbitrary code on
vulnerable installations of Cisco Secure Desktop. User interaction is
required to exploit this vulnerability in that the target must visit a
malicious page or open a malicious file.

The specific flaw exists within CSDWebInstaller.ocx ActiveX control. The
vulnerable Cisco-signed ActiveX control verifies the signing authority
names in the certificate chain but fails to properly verify the digital
signature of an executable file that is downloaded and executed by the
Cisco Secure Desktop installation process. A remote attacker can exploit
this vulnerability to execute arbitrary code under the context of the
browser.

-- Vendor Response:
February 23, 2011 - This vulnerability is being disclosed publicly without a patch in accordance with the ZDI 180 day 
deadline. 

-- Mitigations:
Cisco states that they will have a patch for this issue on March 31st, 2011. In the meantime, we suggest users implement the mitigations below.

The killbit can be set on this control to disable scripting within Internet Explorer by modifying the data value of the Compatibilty Flags DWORD within the following location in the registry:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\705EC6D4-B138-4079-A307-EF13E4889A82

If the Compatibility Flags value is set to 0x00000400 the control can no longer be instantiated inside the browser. For more information, please see: http://support.microsoft.com/kb/240797

-- Disclosure Timeline:
2010-09-14 - Vulnerability reported to vendor
2011-02-23 - Coordinated public release of advisory

-- Credit:
This vulnerability was discovered by:full
    * Anonymous

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