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Re: Possible RDP vulnerability
From: wicked clown <wickedclownuk () googlemail com>
Date: Fri, 26 Mar 2010 15:30:40 +0000

Thank you for your comment.

What I was referring to it being scary is that if you create a locked down
group policy that is tighter than a ducks bum and you forget that single
tick (I admit I didn't knew of that option and I bet lots of other people
didn't know about it) you leave your system to total pwnage!! It's simple
mistakes like that which compromises systems.

If I found this before MS10-015 patch was released I could of download that
exploit and gain system level permission, so no user based permission or
access control would of stopped me.



On Fri, Mar 26, 2010 at 2:13 PM, Thor (Hammer of God)
<Thor () hammerofgod com>wrote:

There’s nothing “scary” about it.   I believe you are incorrectly asserting
that the inclusion of the “start the following program on connection” has
something to do with “locking down the server” and/or “only allow(ing) users
who connect to your server to run certain applications.”   I would suggest
that you study up on what RDP is and how it works before posting things like
this.



Consider “locking down RDP” a process similar to “locking down a local
host.”  Use permissions and other host/OS based controls to secure what a
user can and can’t do on a host.



t







*From:* full-disclosure-bounces () lists grok org uk [mailto:
full-disclosure-bounces () lists grok org uk] *On Behalf Of *wicked clown
*Sent:* Friday, March 26, 2010 3:33 AM

*To:* Full-Disclosure () lists grok org uk
*Subject:* Re: [Full-disclosure] Possible RDP vulnerability



Cheers for that,

I take it back that I haven't found an vulnerability :(, but by default
this isn't enabled which is scary !!


On Fri, Mar 26, 2010 at 9:57 AM, Mr. Hinky Dink <dink () mrhinkydink com>
wrote:

There is a section in RCP-Tcp Properties on the server under "Environment"
for "Do not allow an initial program to be launched.  Always show the
desktop".



----- Original Message -----

*From:* wicked clown <wickedclownuk () googlemail com>

*To:* Full-Disclosure () lists grok org uk

*Sent:* Friday, March 26, 2010 5:04 AM

*Subject:* [Full-disclosure] Possible RDP vulnerability



Hi Guys,



I think I possible may have found a vulnerability with using RDP / Terminal
services on windows 2003.



If you lock down a server and only allow users who connect to your RDP
connection to run certain applications, users can bypass this and run ANY
application they want. You can do this by modifying the RDP profile /
shortcut and add your application to the alternate shell and the shell
working directory.



When the user connects now to the RDP server the banned application will
execute upon logging on even though the user isn’t allowed to execute the
application if the user logs on normally. This doesn’t work with cmd.exe but
I have been able to execute internet explorer, down a modified cmd version,
modify the RDP profile to execute the new cmd and it works like a charm.



I have only been able to tested this on windows 2003 using a local policy
and works like a treat. Even in the wild!



I have done a quick basic video which can been seen here;

http://www.tombstone-bbs.co.uk/v1d30z/rdp-hack2.swf



Instead of modifying the RDP profile, I just added my application to the
program tab.. I know the video is crappy but it’s just meant to give you an
idea what I am talking about :)



So in short, if anybody can access your server via RDP they are NOT
restricted by the policy. I would be interested in any feed back about this
possible exploit / vulnerability even if you don’t think it is.. or even
better if someone knows how to defend againest it!! LOL! :)



Cheers

Wicked Clown.
------------------------------

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Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/



_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/

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