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Terminal Services - How safe are we for remote admin?

Posted on 2006-06-30
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Last Modified: 2010-04-20
I've been debating the safety of Terminal Services with a couple other IT professionals and I'd like to see if we can reach a consensus. Here's the facts of a typical situation:

1. Small network with just one file server
2. Windows 2003 Server or Windows 2003 Small business Server
3. Netgear or Linksys router with a cable modem attached.
4. Static IP address is assigned to the router or they are using DYNDNS.ORG
5. Router has port 3389 forwarding to the internal LAN address of the server.
6. The administrator account has permission to log in remotely via Terminal Services (RDP) as either a normal user or with the /console switch to gain console access.
7. Assume strong passwords are enforced on the server

The issue of debate is: How risky is this scenario?

I'd love to get as many opinions as I can.

Thanks!

Paul



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Question by:paul_lcs
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15 Comments
 
LVL 13

Expert Comment

by:prashsax
ID: 17019846
Rename your administrator account.
This provide an attacker a point to start attack.

If you want real secure access to your Server, you can consider using hamachi.(http:www.hamachi.cc)
Its a free vpn product, and can connect any number of machines securly.





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Author Comment

by:paul_lcs
ID: 17020830
Thank you for the comment Prashsax. I'll check out the site you referenced.  

The question though is how great a risk is this without a VPN? Assuming remember that the accounts use strong passwords and not dictionary words, how can security be compromised?
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LVL 13

Assisted Solution

by:prashsax
prashsax earned 100 total points
ID: 17020958
People do use Terminal Services over internet and with proper setup it can provide good security.

In Windows Server 2003, you can configure TS to use TLS for server authentication and data encryption. This is extremely important for anyone running TS over the Internet.

http://support.microsoft.com/?id=895433
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LVL 48

Assisted Solution

by:Jay_Jay70
Jay_Jay70 earned 100 total points
ID: 17022014
it isnt a bad setup that you have, and a very common one for small business without VPN capabilities, ideally, a VPN server would be more secure, but as long as you have strong authentication rules as mentioned above, you should be ok
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LVL 51

Assisted Solution

by:Keith Alabaster
Keith Alabaster earned 300 total points
ID: 17028218
Paul, a further lock down will be to restrict the source addresses. Set the external router/firewall/whatever to only allow port 3389 from selected source addresses to the servers.

If you are running SBS and ISA server or a good firewall, you can further lock it down by changing ths source ports and then redirecting them to 3389 as a further security measure.

In truth, ANY hole that you make in your external security perimter is exactly that; a hole. The best you can do is to minimise the risk of the hole.

Regards
Keith
0
 

Author Comment

by:paul_lcs
ID: 17207424
I guess if we can't leave it open longer, then we can't leave it open longer. This is an important topic and I was hoping to get more responses.
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LVL 51

Expert Comment

by:Keith Alabaster
ID: 17235032
I am happy to continue working on this one subject to some feedback or further clarification/streamlining of the requirement.

Regards
keith
0
 

Author Comment

by:paul_lcs
ID: 17274001
Thanks Keith.

It seems there's a knee-jerk reaction when someone says "Hey, you've opened a port up so now your machine is exposed to the internet." I'm really trying to get my arms around whether this really is a serious and exploitable threat.

See Prashsax first response suggesting the use of a VPN. Of course VPN is fine, but that would require clientside configuration and ultimately, maintenance.

Paul
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LVL 51

Accepted Solution

by:
Keith Alabaster earned 300 total points
ID: 17283033
This is true but it is fairly uniform across the board. SBS has one of the more secure functions though in that you can use the SBS wizards to actually create the VPN configuration locally with the CMAK (Connection Manager). The only VPN options you have with practically zero maintenance are the SSL VPN's (web-based) such as that provided on the Cisco concentrators or the newer all-in-one units and letting these call the //SBS_server/TSWEB.

Setting up the RADIUS services linked to the SSL concentrator for authentication, the user must authenticate first to get onto the concentrator from outside; the concentraor stops the user and presents the http//server/tsweb page allowing you to login to the server(s) you want to administrate but still needs the full username/password combo. Neat part is that the external user never actually gets onto the internal network as the concentrator proxies the requests plus zero maintenance on the client as it is called from a web browser.

Link the RADIUS into your active directory and you have a good, secure base, no remote administration on a client.

SBS is a cool product.

Regards
Keith

0
 

Author Comment

by:paul_lcs
ID: 17295085
Yeah, that does sound pretty cool, but in your assessment, how hard is it to set up and get working? I heard RADIUS wasn't real simple. - Lots of steps and lots to go wrong.

And what to do about those not running SBS?

Paul
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LVL 51

Expert Comment

by:Keith Alabaster
ID: 17297378
SBS (Microsoft) has its own RADIUS server and is wizard driven. The Concentrator just makes the call back to the SBS boxYes, it is another area that 'could' be a point of failure although in itself it is another security point. You make your decision based upon the level of security either the data you are protecting (or your company IT Policy) dictates.
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LVL 51

Expert Comment

by:Keith Alabaster
ID: 17301177
Thank you :)
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