[NT] Nortel Contivity VPN Client Privilege Escalation

From: SecuriTeam (support_at_securiteam.com)
Date: 08/14/05

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Date: 14 Aug 2005 17:49:55 +0200

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      Nortel Contivity VPN Client Privilege Escalation
    ------------------------------------------------------------------------

    SUMMARY

    The Contivity VPN Client is a Windows application that lets you define and
    store connection information for accessing your corporate network through
    a Contivity Secure IP Services Gateway. When the Contivity client is
    running as a service it is possible to manipulate the interface of the
    client and escalate privileges to that of the LocalSystem account.

    DETAILS

    Vulnerable Systems:
     * Nortel Contivity VPN Client version 05_01.030

    By using the Digital Certificate Authentication Entrust attackers may
    receive console with the permission of LocalSystem account that will
    result in a privileges escalation, and will allow attackers to execute
    arbitrary programs, with that LocalSystem privilege.

    Proof of Concept:
      1. With the Contivity client open click on Options and select
    Authentication Options.
      2. Select Digital Certificate Authentication Entrust and click OK.
      3. To the right of the certificate box click the button icon and select
    open.
      4. Change Files of type: to All Files, navigate to the system32
    directory and locate cmd.exe. Right click cmd.exe and choose Open.

    It should also be noted that this exploit can be carried out by running
    the connection wizard and following steps 2-4.

    The result is a command prompt running under the context of the
    LocalSystem account.

    Vendor Status:
    The vendor was notified of the issue and an updated version has been
    released.

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:jeff.peadro@gmail.com> Jeff
    Peadro.

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