[NT] Nortel Contivity VPN Client Privilege Escalation

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Nortel Contivity VPN Client Privilege Escalation
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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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