Paul,
The smartest and best thing to do if you must open the terminal services
port to the world is to change the port that terminal services runs on.
I do this, and it never gets attacked. You should also change the name
of your administrator account. This is best practice. I've had my
terminal server accessible to the worls for literally year now with no
problems.
Read this and give it a shot.
http://support.microsoft.com/default.aspx?scid=kb;en-us;q187623 When
you connect using the terminal services client, you put a : and the port
number after the server name, like this, server:6432
-steve
________________________________
From: Paul Greene [mailto:techlists@comcast.net]
Sent: Fri 11/11/2005 9:18 PM
To: focus-ms@securityfocus.com
Subject: break in?
Hello,
I have a Win2K domain controller running on my home network that had
Terminal Services enabled through my firewall so that I could access the
box from my office at work. I had configured the firewall to only all TS
access from the IP block of the company where I work. (the firewall is
an openbsd box that also acts as the gateway to my ISP)
Well, I went out on a road trip and allowed TS access from "any" so that
I could access the DC from my hotel room, and then forgot to restrict
access again when finished. Ooops!! Big mistake.
I was looking through Event viewer troubleshooting another issue a few
days ago, then noticed a whole bunch of failed administrator logins in
the security logs. Oh, crap what happened now. I ran Symantec AV, Spybot
search and destroy, and Adware and none of them found anything. I ran MS
Update service and realized I was out of date on several patches (going
back about 2 months worth of patches).
Another ominous sign was that the DC had two printers configured that I
use at the office, but I have never configured a printer for this DC. I
deleted the printers, and they came right back.
I wanted to see what was going on with the DC, so rather than wipe it
clean and re-install, I locked the firewall down real tight and started
logging everything to see if the DC was going to try to "phone home"
somewhere. I'm only allowing outgoing http access to the MS Update site,
and outgoing DNS queries (UDP port 53) because this is also the dns
server for the network.
More ominous signs. The server was trying a few times a day to make
connection attempts to some outbound websites and ftp sites. Some of the
IP addresses were located in Rumania and Poland. All connection attempts
were getting blocked and logged.
Based on these symptoms, can anyone tell me what happened? In
particular, for educations sake, can anyone tell what the specific
exploit that was used in this case, and possibly a reference where I can
go analyze further what happened?
I don't have anything especially valuable on this server, so I won't
lose much by wiping it and starting over again. I think I've also locked
it down enough now with firewall ACL's that some turkey isn't going to
be stealing my bandwidth for some nefarious purpose either.
Thanks in advance,
Paul Greene
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