Re: Citrix application breakout - take care of Microsoft calculator

[infolookup () gmail com]

A discussion of this nature started a while back where someone noted that you could if giving regular user rights on a 
Citrix terminal still browse the network for shares.

Right click your desktop, select new shortcut and browse to system32/cmd.exe get a list of host name and available 
shares.

 Then open up MS word and create a link to the share, click on it then you are browsing the share, or network place in 
question, in some cases you can even browse the underlining Citrix server that you are connected too, or create a 
folder and copy anything to it.
Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: "Erik Soosalu" <eriks () nationalfastfreight com>

Date: Mon, 10 Mar 2008 12:50:40 
To:<pen-test () securityfocus com>
Subject: RE: Citrix application breakout - take care of Microsoft calculator


Once you're  in Notepad, File->Open, browse to Windows/system32, find cmd.exe right click and open and you have a 
command prompt on the box.  Of course, your could specify any UNC and get a file to load from wherever you want.  Not 
sure what the actual run permissions would be....
 
Erik
 
 

________________________________

From: listbounce () securityfocus com on behalf of Stefan Gora
Sent: Fri 3/7/2008 6:13 AM
To: pen-test () securityfocus com
Subject: Citrix application breakout - take care of Microsoft calculator



Dear all,

I'm not shure if the following issue is already known or exciting,
nevertheless the following attack vector found during a penetration test
might be interesting:

A customer has built a Citrix environment for a partner company to
provide access to a specific application. This application was intended
to be the only application accessible for this partner. It was possible
to get a remote task manager with CRTL-F3, but no other way of
interacting with the Citrix Server (e.g. through printing or so).

Unfortunately they have integrated Microsoft's calculator into the
application. A bad idea - guess why ;-).

Using the calculator you are able to do funny stuff: Open the calculator
and click "info". Klick on the licence agreement and here you go, you
have got an editor. With this you can use "open file" and browse the
server, find for example Word and rightclick on "Open" - Word is
running, and all other applications which you like as well ...

I think this can easily be fixed using more restrictive file
permissions, but I thought maybe some of you might find this information
useful.

Stefan

--
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Identity Management Symposium 22.-23.04.2008 KA/Ettlingen
http://www.identity-management-symposium.de <http://www.identity-management-symposium.de/> 
--------------------------------------------------------

Stefan Gora
Security Consultant

Secorvo Security Consulting GmbH
Ettlinger Strasse 12-14, D-76137 Karlsruhe
Tel. +49 721 255171-302, Fax +49 721 255171-100
stefan.gora () secorvo de, http://www.secorvo.de <http://www.secorvo.de/> 
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Mannheim HRB 108319, Geschaeftsfuehrer: Dirk Fox

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