Full Disclosure: Re: Possible RDP vulnerability

["Mr. Hinky Dink" <dink () mrhinkydink com>]

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 
  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
Hosted and sponsored by Secunia - http://secunia.com/