[c-nsp] Cisco Security Advisory: Windows VPN Client Local Privilege Escalation Vulnerability

Wed May 24 11:25:44 EDT 2006

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Cisco Security Advisory: Windows VPN Client Local Privilege Escalation
Vulnerability

Document ID: 70332

Advisory ID: cisco-sa-20060524-vpnclient

http://www.cisco.com/warp/public/707/cisco-sa-20060524-vpnclient.shtml

Revision 1.0

For Public Release 2006 May 24 1600 UTC (GMT)

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Contents
========

    Summary
    Affected Products
    Details
    Impact
    Software Versions and Fixes
    Workarounds
    Obtaining Fixed Software
    Exploitation and Public Announcements
    Status of This Notice: INTERIM
    Distribution
    Revision History
    Cisco Security Procedures

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Summary
=======

The Cisco VPN Client for Windows is affected by a local privilege
escalation vulnerability that allows non-privileged users to gain
administrative privileges.

A user needs to authenticate and start an interactive Windows session
to be able to exploit this vulnerability.

Cisco has made free software available to address this vulnerability
for affected customers.

This advisory is posted at 
http://www.cisco.com/warp/public/707/cisco-sa-20060524-vpnclient.shtml .

Affected Products
=================

Vulnerable Products
+------------------

The following versions of the Cisco VPN Client for Windows (excluding
Windows 9x users) are affected:

  * 2.x
  * 3.x
  * 4.0.x
  * 4.6.x
  * 4.7.x with the exception of version 4.7.00.0533 (see below in
    Products Confirmed Not Vulnerable.)
  * 4.8.00.x

Products Confirmed Not Vulnerable
+--------------------------------

All other versions of Cisco VPN Client that are based on an operating
system other than Microsoft Windows are not affected by this
vulnerability. These include:

  * Any version of the Cisco VPN Client for Solaris
  * Any version of the Cisco VPN Client for Linux
  * Any version of the Cisco VPN Client for Macintosh (MacOS X and
    MacOS Classic)

Cisco VPN Client for Windows version 4.8.01.x and later are not
affected by this vulnerability.

In addition, due to a regression, version 4.7.00.0533 of the Cisco VPN
Client for Windows is not affected, even though other 4.7.x are
affected. Users running version 4.7.00.0533 of the Cisco VPN Client for
Windows do not need to upgrade to version 4.8.01 or later to be
protected from this vulnerability.

No other Cisco products are currently known to be affected by this
vulnerability.

Determining the Cisco VPN Client Version
+---------------------------------------

In order to determine which version of the Cisco VPN Client is running
on the Microsoft Windows machine, open the Cisco VPN Client graphical
user interface by selecting "Programs->Cisco Systems VPN Client->VPN
Client" from the Start menu and then select the option "About VPN
Client..." from the "Help" menu. This will display a dialog box
containing text similar to "Cisco Systems VPN Client Version 
4.0.5(Rel)". Please note that the location of the "Cisco Systems VPN 
Client" folder mentioned above in Windows' Start menu is where the 
program is installed by default; your system administrator may have 
chosen to use a different name or location.

Details
=======

The Cisco VPN Client is a software solution for the Sun Solaris, Apple
MacOS Classic and MacOS X, Linux and Microsoft Windows operating
systems that allows users running these operating systems to establish
IPSec VPN tunnels to Cisco VPN-capable devices like Cisco IOS routers,
the PIX Security Appliance, the VPN 3000 Series Concentrators, and the
ASA 5500 Series Adaptive Security Appliances.

A vulnerability in the Cisco VPN Client for Windows Graphical User
Interface (GUI), also known as the "VPN client dialer", can be
exploited to elevate user privileges and obtain LocalSystem-equivalent
privileges.

This issue is not related to any known issues in Microsoft Windows
itself.

This vulnerability is documented by Cisco Bug ID CSCsd79265. 

For information about local system level privileges, please refer to:

  * The LocalSystem Account
    http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/localsystem_account.asp

Impact
======

Successful exploitation of the vulnerability may result in a normal
user or attacker gaining full control of the system, evading any
controls put in place by the Windows system administrator.

Software Versions and Fixes
===========================

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.

This vulnerability is fixed in version 4.8.01.0300 of the Cisco VPN
Client for Windows, which can be downloaded from the following
location:

http://www.cisco.com/pcgi-bin/tablebuild.pl/windows 

For information on how to upgrade the Cisco VPN Client, including
automatic upgrades, please refer to the following chapter of the VPN
Client Administrator Guide: Updating VPN Client Software.

Workarounds
===========

There are no workarounds for this vulnerability.

Obtaining Fixed Software
========================

Cisco has made free software available to address this vulnerability
for affected customers. Prior to deploying software, customers should
consult their maintenance provider or check the software for feature
set compatibility and known issues specific to their environment.

Customers may only install and expect support for the feature sets they
have purchased. By installing, downloading, accessing or otherwise
using such software upgrades, customers agree to be bound by the terms
of Cisco's software license terms found at 
http://www.cisco.com/public/sw-license-agreement.html, or as otherwise 
set forth at Cisco.com Downloads at 
http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

Do not contact either "psirt at cisco.com" or "security-alert at cisco.com"
for software upgrades.

Customers with Service Contracts
+-------------------------------

Customers with contracts should obtain upgraded software through their
regular update channels. For most customers, this means that upgrades
should be obtained through the Software Center on Cisco's worldwide
website at http://www.cisco.com.

Customers using Third-party Support Organizations
+------------------------------------------------

Customers whose Cisco products are provided or maintained through prior
or existing agreement with third-party support organizations such as
Cisco Partners, authorized resellers, or service providers should
contact that support organization for guidance and assistance with the
appropriate course of action in regards to this advisory.

The effectiveness of any workaround or fix is dependent on specific
customer situations such as product mix, network topology, traffic
behavior, and organizational mission. Due to the variety of affected
products and releases, customers should consult with their service
provider or support organization to ensure any applied workaround or
fix is the most appropriate for use in the intended network before it
is deployed.

Customers without Service Contracts
+----------------------------------

Customers who purchase direct from Cisco but who do not hold a Cisco
service contract and customers who purchase through third-party vendors
but are unsuccessful at obtaining fixed software through their point of
sale should get their upgrades by contacting the Cisco Technical
Assistance Center (TAC). TAC contacts are as follows.

  * +1 800 553 2447 (toll free from within North America)
  * +1 408 526 7209 (toll call from anywhere in the world)
  * e-mail: tac at cisco.com

Have your product serial number available and give the URL of this
notice as evidence of your entitlement to a free upgrade. Free upgrades
for non-contract customers must be requested through the TAC.

Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml
for additional TAC contact information, including special localized
telephone numbers and instructions and e-mail addresses for use in
various languages.

Exploitation and Public Announcements
=====================================

The Cisco PSIRT is not aware of any public announcements or malicious
use of the vulnerability described in this advisory.

This vulnerability was independently reported to Cisco by Andrew
Christensen from FortConsult and by Johan Ronkainen. Cisco would like
to thank them for working with us towards coordinated disclosure of
this vulnerability.

Status of This Notice: INTERIM
==============================

THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY
KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE
INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT
YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS
DOCUMENT AT ANY TIME. CISCO EXPECTS TO UPDATE THIS DOCUMENT AS NEW
INFORMATION BECOMES AVAILABLE.

A stand-alone copy or Paraphrase of the text of this document that
omits the distribution URL in the following section is an uncontrolled
copy, and may lack important information or contain factual errors.

Distribution
============

This advisory is posted on Cisco's worldwide website at 
http://www.cisco.com/warp/public/707/cisco-sa-20060524-vpnclient.shtml .

In addition to worldwide web posting, a text version of this notice is
clear-signed with the Cisco PSIRT PGP key and is posted to the
following e-mail and Usenet news recipients.

  * cust-security-announce at cisco.com
  * first-teams at first.org
  * bugtraq at securityfocus.com
  * vulnwatch at vulnwatch.org
  * cisco at spot.colorado.edu
  * cisco-nsp at puck.nether.net
  * full-disclosure at lists.grok.org.uk
  * comp.dcom.sys.cisco at newsgate.cisco.com

Future updates of this advisory, if any, will be placed on Cisco's
worldwide website, but may or may not be actively announced on mailing
lists or newsgroups. Users concerned about this problem are encouraged
to check the above URL for any updates.

Revision History
================

+----------------------------------------+
| Revision |             | Initial       |
| 1.0      | 2006-May-24 | public        |
|          |             | release.      |
+----------------------------------------+

Cisco Security Procedures
=========================

Complete information on reporting security vulnerabilities in Cisco
products, obtaining assistance with security incidents, and registering
to receive security information from Cisco, is available on Cisco's
worldwide website at 
http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html.
This includes instructions for press inquiries regarding Cisco security 
notices. All Cisco security advisories are available at 
http://www.cisco.com/go/psirt.

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Updated: May 24, 2006                                Document ID: 70332

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