Vulnerability Note VU#339177

Cisco AnyConnect Clientless SSL VPN Portforwarder ActiveX control buffer overflow

Original Release date: 14 Mar 2012 | Last revised: 24 Jul 2014


The Cisco AnyConnect ActiveX control contains a buffer overflow vulnerability, which can allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.


Cisco AnyConnect is an SSL VPN solution that is commonly initiated through use of a web browser. When Internet Explorer is used, the AnyConnect VPN server provides an ActiveX control that downloads and installs the AnyConnect client software. One of the components provided by Cisco AnyConnect for use with Internet Explorer is an ActiveX control called the "CISCO Portforwarder Control." This ActiveX control is provided by the file ciscopf.ocx. The Cisco Portforwarder ActiveX control contains a buffer overflow in its initialization parameters. We have confirmed that version of the Portforwarder control is vulnerable. Previous versions may also be affected.


By convincing a user to view a specially crafted HTML document (e.g., a web page or an HTML email message or attachment), an attacker may be able to execute arbitrary code.


Apply an update

This issue is addressed in Cisco Security Advisory cisco-sa-20120314-asaclient. Please note that updating a Cisco ASA device with the fixed software will not protect systems that have already downloaded the vulnerable control. Please also consider the following workarounds:

Disable the Cisco AnyConnect Portforwarder ActiveX control in Internet Explorer

The vulnerable Cisco AnyConnect Portforwarder ActiveX control can be disabled in Internet Explorer by setting the kill bit for the following CLSID:

More information about how to set the kill bit is available in Microsoft Support Document 240797. Alternatively, the following text can be saved as a .REG file and imported to set the kill bit for this control:
    Windows Registry Editor Version 5.00

    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{B8E73359-3422-4384-8D27-4EA1B4C01232}]
    "Compatibility Flags"=dword:00000400
    [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\ActiveX Compatibility\{B8E73359-3422-4384-8D27-4EA1B4C01232}]
    "Compatibility Flags"=dword:00000400

Vendor Information (Learn More)

VendorStatusDate NotifiedDate Updated
Cisco Systems, Inc.Affected16 Jun 201114 Mar 2012
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C
Temporal 7.3 E:POC/RL:OF/RC:C
Environmental 5.5 CDP:ND/TD:M/CR:ND/IR:ND/AR:ND



This vulnerability was reported by Will Dormann of the CERT/CC

This document was written by Will Dormann.

Other Information

  • CVE IDs: CVE-2012-0358
  • Date Public: 14 Mar 2012
  • Date First Published: 14 Mar 2012
  • Date Last Updated: 24 Jul 2014
  • Severity Metric: 11.03
  • Document Revision: 22


If you have feedback, comments, or additional information about this vulnerability, please send us email.