NCP VPN/PKI Client - various Bugs Mar 01 2006 06:20PM
Ramon 'ports' Kukla (ml2 portsonline net)
Application: NCP VPN/PKI Client
Site: http://www.ncp.de
Version: 8.11, Build 146 and maybe lower
OS: Windows
Bugs: Local Privilige Escalation, DoS and other

NCP's Secure Communications provides a comprehensive portfolio of
products for implementing total solutions for high-security remote
access. These software-based products comply fully with all current
major technology standards for communication and encryption, as defined
by the IETF (Internet Engineering Task Force) and ITU (International
Telecommunication Union). Consequently all products can be smoothly
integrated into any existing network and communication architectures.
Your Internet infrastructure, which may already consist of third-party
security and access components, can be further used without changes ?
thus avoiding any unnecessary administrative costs.


I found a few Bugs/Problems in the NCP VPN/PKI Client. If you read this
post you probably notice that this list of errors and bugs is just the
result of some really short tests. I'm *really* sure that there are
still some nice bugs.

1.: - Unnamed
If you create a rule using the Client Firewall you're able to bind an
application to this rule. Unfortunately no hash value (for instance)
will be created for this application. So you can easily pick another
application, put it into the directory, rename it and use it with this

NCP is aware about this problem. A later version of the client will
come with a hash-function.

2.: - Buffer Overflow with Privilege Escalation (some sort of), DoS
Some of the installed applications didn't like it to start with a large
amount of arguments.

example 1:
In my current test-configuration I'm not able to go to or configure
'IPSec' in the menu 'configuration'. If I run 'ncpmon.exe' with >=261
characters I get a slightly different gui. And it's not only the gui
which is different. Now I'm able to go to the 'IPSec' menu and
configure the settings.

example 2:
Run 'ncprwsnt.exe' with enough arguments and your cpu utilization will
raise 100%.

NCP is currently checking this problem(s).

3: - DoS, remote
I picked the first DoS code I found, tried it and was surprised that
this old piece of code is still working. Using the 'ZoneAlarm remote
Denial Of Service exploit'[1] it's possible to raise the memory usage
and the cpu utilization. Let it run for 1-2 minutes and you will notify
the decreasing speed of your machine. And at least it's possible to
make it impossible for you to continue working with the pc.

NCP is currently checking this problem(s).

4: - Local Privilege Escalation
One feature of the client is that you can execute a script called
'connect.bat' after you established a connection with your vpn-gateway.
The script isn't executed by the client, but by the service 'ncprwsnt'
which runs with the local system account. So add a little script in the
program dir of the NCP VPN/PKI Client with a nice 'net user /add' and
'net localgroup /add' mix to escalate your privileges.

This 'Feature' is known to NCP. A couple of customers are using exactly
this functionality. A new relase of the NCP VPN/PKI Client, which will
arrive in the next few weeks, will fix this 'problem'.

2006-02-13: Found the Bugs
2006-02-15: Mailed the vendor
2006-02-16: The vendor replied

Thanks to the really nice and cool support from ncp :)


[1] http://cert.uni-stuttgart.de/archive/bugtraq/2003/09/msg00020.html

SYS 64767

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