RE: Windows Remote Desktop

["Nero, Nick" <Nick.Nero () disney com>]

You can use Citrix's http gateway with full SSL which will prevent MITM
attacks.  If you wanted to you, you may be able to use certificate
authentication for MS RDP.  I agree that MS RDP is very secure over
LANS, but over the net you may want to PPTP/IPSEC the traffic via vpn.
Another solution is to use WINSSHD
(http://www.bitvise.com/remote-desktop.html) and tunnel the RDP session
in SSH.  I think this would make an RDP session as close to unbreakable
as you can get.

I didn't put much work into this response so it is only .01.  And even
that is in pesos. 

-----Original Message-----
From: Depp, Dennis M. [mailto:deppdm () ornl gov] 
Sent: Thursday, January 15, 2004 4:14 PM
To: Shawn Jackson; jamesworld () intelligencia com
Cc: Michael Gale; security-basics () securityfocus com
Subject: RE: Windows Remote Desktop

Shawn,

I still fail to see the difference between Citrix and RDP as far as
security goes.  RDP like Citrix can be configured on the server side.
As for the MiM attack.  Theoretically I can setup an machine and have it
masquerade as your Citrix server.  When you logon to my machine you
enter your Username and Password.  I pass this information on to your
Citrix server and I have compromised your data.  This is possible
because no authentication is done at the client to ensure your machine
is authentic.  This is true for both the HTTP interface/gateway and the
ICA client.  The same also holds true for the RDP protocol.  (Which I
believe has a lot of Citrix components in it.)

I still don't want end users accessing their home workstation via RDP,
Citrix, PCAnywhere, VNC or any other protocol.  This creates another
portal into my network for virii and worms.  

Denny 

-----Original Message-----
From: Shawn Jackson [mailto:sjackson () horizonusa com]
Sent: Thursday, January 15, 2004 3:52 PM
To: Depp, Dennis M.; jamesworld () intelligencia com
Cc: Michael Gale; security-basics () securityfocus com
Subject: RE: Windows Remote Desktop


        Citrix ICA defaults to the setting on the server side, so if you
configured your server with *some* security then a 'basic default' is
not the case. Personally I separate raw data (Files, Databases, etc) and
interactive 'streaming' data. Raw data is a file/component in transit on
the wire that can be sniffed and recompiled, while streaming data can't
be recompiled into anything but can be sifted through for information.

        Capturing interface information from even an unencrypted RDP
connection is difficult. Setup three workstations on a hub then setup
VNC server on 1 and the viewer on the 2nd. From the 3rd workstation use
SNORT and sniff the traffic between the two. Have another person play
with the viewer to give you something too look at.

        To my understanding Citrix is only at risk of a MiM attack when
using the HTTP interface/gateway and not the ICA client. If I'm
incorrect please supply a link to information about this attack. Also I
don't believe you can use SSL with XP RDP and that's Terminal Services.

        Personally I can justify the need of using RDP to my workstation
at home, but then again I know that system and its security. I setup and
maintain that network and servers so I can be reasonably sure that my
connection is clean and my systems are not at risk. Would I personally
let my users have RDP access to their workstations at home, nope. My
reasoning for this is that they could be violating the company policy
(browsing bad sites, playing games, listening to their MP3 collection,
etc) and we can't see it. Would I let our IT/IS guys, yep. I'm not
worried about people taking data offsite because everyone has USB drives
already. I'm also not *too* worried about virii or hackers; it's that it
just walks too fine a line with our security policy. But then again, if
them have a business need...

        My 2,000,000 cents! :-)

Shawn Jackson
Systems Administrator
Horizon USA
1190 Trademark Dr #107
Reno NV 89521

www.horizonusa.com
Email: sjackson () horizonusa com
Phone: (775) 858-2338
             (800) 325-1199 x338


-----Original Message-----
From: Depp, Dennis M. [mailto:deppdm () ornl gov] 
Sent: Thursday, January 15, 2004 10:29 AM
To: Shawn Jackson; jamesworld () intelligencia com
Cc: Michael Gale; security-basics () securityfocus com
Subject: RE: Windows Remote Desktop

Two statements I don't agree with:

1)  "Additionally no actual 'data' is transferred through the RDP
connection, it's just interface information (mouse movement, button
clicks, typing) and screen refreshes. Now if you were using the resource
mapping then data would traverse the RDP connection and would be subject
to its encryption."
        Data is sent over the wire concerning keystrokes, mouse
movements and screen refresh data. Obviously this information,
particularly keystrokes can provide data to a hacker.  However all
information set via RDP is encrypted the default is 56-bit with the
capacity to use 128-bit RC4.  Even when using local resources, the data
is still encrypted with 128-bit security.  

2) "All in all I think that PCAnywhere and Citrix have
more secure RDP/VNC like interfaces"   
        The default security setting in Citrix is basic (no encryption)
PCAnywhere maybe better, I'm not sure.  Both Citrix and RDP are
vulnerable to MiM attacks.  Citrix does have the capability to use SSL
but this is comprable to Microsoft's VPN solution.

Denny

-----Original Message-----
From: Shawn Jackson [mailto:sjackson () horizonusa com] 
Sent: Wednesday, January 14, 2004 6:36 PM
To: jamesworld () intelligencia com
Cc: Michael Gale; security-basics () securityfocus com
Subject: RE: Windows Remote Desktop


        Well transferring data outside a company is easier then pie
these days. With everything from encrypted email to USB drives it's hard
to use that as a sole point 'ban' RDP to offsite resources. Unless
you're running at high level security i.e. Military, Extremely Sensitive
Work, National Security the movement of data offsite would be a
secondary concern.

        The RDP encryption is 'in transit' protection and won't protect
the resources. I personally never use the clipboard sharing,
drive/printer mapping, etc. Access to those resources should be dictated
by the company security policy and doesn't follow the 'security' of the
protocol/connection. Seaming the connection is one-way (From Workstation
or RDP Host) it hard to open a hole/exploit through an infected RDP host
and use the RDP interface to your advantage.

        Additionally no actual 'data' is transferred through the RDP
connection, it's just interface information (mouse movement, button
clicks, typing) and screen refreshes. Now if you were using the resource
mapping then data would traverse the RDP connection and would be subject
to its encryption. All in all I think that PCAnywhere and Citrix have
more secure RDP/VNC like interfaces but RDP is pretty secure by itself.
Just as James stated, watch the local resource mapping.

Shawn Jackson
Systems Administrator
Horizon USA
1190 Trademark Dr #107
Reno NV 89521

www.horizonusa.com
Email: sjackson () horizonusa com
Phone: (775) 858-2338
             (800) 325-1199 x338

-----Original Message-----
From: jamesworld () intelligencia com [mailto:jamesworld () intelligencia com]

Sent: Wednesday, January 14, 2004 3:03 PM
To: Shawn Jackson
Cc: Michael Gale; security-basics () securityfocus com
Subject: RE: Windows Remote Desktop

Ahh,,


but what about the option to connect local resources......

Drives
Printers
Serial Ports
Smart Cards

....

Talk about the ability to transfer company data out...  What is
protecting 
the actual data, MS RDP encryption  which defaults to "medium" security
by 
default.

Again it comes back to.......What is the company policy?  If it doesn't 
cover it, the policy needs to be updated.


-James

At 12:14 01/14/2004, Shawn Jackson wrote:

>         Eh' for 'Testing' I use a remote SSH server off my backbone. I
> do 'periodically' login to my remote XP workstation and do some work.
> Because only screen information is transmitted even if that system was
> hacked or infected with a virus it won't affect my network at work. My
> XP system doesn't sit directly on the Internet through; it goes through
> a Debian box running iptables.
>
> Shawn Jackson
> Systems Administrator
> Horizon USA
> 1190 Trademark Dr #107
> Reno NV 89521
> www.horizonusa.com
>
> Email: sjackson () horizonusa com
> Phone: (775) 858-2338
>        (800) 325-1199 x338
>
> -----Original Message-----
> From: Michael Gale [mailto:michael () bluesuperman com]
> Sent: Tuesday, January 13, 2004 8:35 PM
> To: security-basics () securityfocus com
> Subject: Windows Remote Desktop
>
> Hello,
>
>         I have a question, I have locked down a company network
allowing
> only
> web browsing, SSH and FTP. Nothing else is need and soon SSH and FTP
> will be gone hopefully once the VPN is final.
>
> Right now a internal user is complaining about the fact their remote
> desktop connection to their home PC is no longer working.
>
> The justification is that a remote PC out side the network is needed
for
> testing. At which point I gladly offered to setup a out side box for
> testing. :)
>
> Any ways the question I have is, do you feel that Remote Desktop (into
> WinXP) is a secure enough connection to allow it. I mind you that this
> is supposed to be a  outbound connection only but you never know with
> windows.
>
>
> --
> Hand over the Slackware CD's and back AWAY from the computer, your geek
> rights have been revoked !!!
>
> Michael Gale
> Slackware user :)
> Bluesuperman.com
>
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We provide Ethical Hacking, Advanced Ethical Hacking, Intrusion
Prevention, 
and many other technical hands on courses. 
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Ethical Hacking at InfoSec Institute. Mention this ad and get $720 off any
course! All of our class sizes are guaranteed to be 10 students or less.
We provide Ethical Hacking, Advanced Ethical Hacking, Intrusion Prevention,
and many other technical hands on courses.
Visit us at http://www.infosecinstitute.com/securityfocus to get $720 off
any course!
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