So let it be written, so let it be done!
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Methinks yon Timeth doth verily issueth meeth challengeth?
------------------------------------------------------- Jim Harrison MCP(NT4, W2K), A+, Network+, PCG http://isaserver.org/Jim_Harrison/ http://isatools.org Read the help / books / articles! -------------------------------------------------------
-----Original Message----- From: Thor (Hammer of God) [mailto:thor@xxxxxxxxxxxxxxx] Sent: Wednesday, April 13, 2005 20:20 To: [ISAserver.org Discussion List] Subject: [isalist] RE: Terminal Service Port Change?
http://www.ISAserver.org
Not only am I bigger, I'm taller too!! :-p
Let's be specific here... Say you change the TS listen port to 44332... While your most-excellent 10 second 65k port scanner may identity that TCP 44332 is open, you don't know what it is. You'll have to connect with appropriate RDP connect sequence to find out that it is actually TS - (If you have a shake-banner-grab that ID's TS on connect, let me know please.)
To clarify, when I said "standard scanning," I didn't mean port sweeps for whatever responds: I meant people scanning for a particular service. Anyone looking for open RDP will scan the IP range for 3389, and target those boxes. Given that I removed "targeted" attacks from the theater of threat, I maintain that changing the port buys me time to ID an attack. Leaving it at 3389 does not in this scenario.
And while a worm may certainly scan ports to find the vulnerable service it is looking for, it has never been done in any worm whose propagation was a threat. A future worm that targets RDP will look for 3389 specifically, as propagation speed while keeping noise down it the key goal. Even if the
44332 box is vulnerable, it will not be infected. Litchfield's suggestion of rebasing executables to change the jmp address is similar- while a worm may try to brute force the jmp address, none have *ever* done so. If I rebased my SQL install, I could have vulnerable instance of MSSQL that would never fall prey to slammer. The same logic applies.
As security people, I think that while we must always consider what *can* be done, we also must look at what *is* being done. Worm port-sweeps don't
happen. General port-sweeps followed by "all-service-grab-bag-connect-attempts" don't happen. Like I said, in a
directed attack, there is not much help... but if I see RDP cookies on the wire destined for <> 3389, I know something is up, and I know immediately.
Not withstanding your Ninja status, I contend that where appropriate, changing the port does indeed give me level of security one does not have otherwise in most of the "real world" attacks that occur. So, Neener Neener. ;)
Specific to that point Mr Dory, (legal disclaimer: this applies to Greg,
Steve, Jim, and Tom only) if you can tell me what port I'm listening for RDP at my corporate network on, I'll buy you a steak dinner at the Union Grill along with a '91 Alexander Valley Silver Oak. I'll even get some strippers to join us (though I have no idea why you people in Seattle call them "strip bars" when they don't strip, and they ain't bars!) Hell, I'll do it anyway since you're helping with my Blackhat Training! Man, there's this one girl who... Oh, sorry... I digress.
:------P
t
----- Original Message ----- From: "Jim Harrison" <Jim@xxxxxxxxxxxx>
To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx>
Sent: Wednesday, April 13, 2005 7:00 PM
Subject: [isalist] RE: Terminal Service Port Change?
it;http://www.ISAserver.org
Normally I don't disagree with Tim cuz he's bigger than me, but given that port scanning is absurdly simple (every script-kiddie worth their salt can do it in their sleep) I can't see the value in port changing for its own sake. Even I can write a tool that will scan all 65365 TCP and UDP ports in less than 10 seconds. It takes very little more to make a few fingerprinting tests that will tell me what lives at a listening port. The time it takes to make sure everyone and everything involved knows how to use it and that it's properly documented, etc., etc. just makes it not worth the time any more. If you have to do this because of resource restrictions, then so bescanningbut don't play "port-games" just because you can.
------------------------------------------------------- Jim Harrison MCP(NT4, W2K), A+, Network+, PCG http://isaserver.org/Jim_Harrison/ http://isatools.org Read the help / books / articles! -------------------------------------------------------
-----Original Message----- From: Thor (Hammer of God) [mailto:thor@xxxxxxxxxxxxxxx] Sent: Wednesday, April 13, 2005 18:08 To: [ISAserver.org Discussion List] Subject: [isalist] RE: Terminal Service Port Change?
http://www.ISAserver.org
Joking aside, there is actually a very valid reason to change default ports for services where applicable, and that is to avoid "standard"securityand/or worm activity. Greg is absolutely correct in that obscuring a service via port change will not thwart a directed attack, butthrough obscurity does work as long as the target remains obscure.RDPbox
services on alt ports are difficult to detect unless you can hit thesessions
with RCP and are an admin (without port scanning by instantiating a TS handle), or unless you can hit the box with NetBIOS and proxy requests for server registration through the Master Browser (even with nullOfon weak Win2k installs).
To speak to that old argument, I would say to do *both* if you can.recommend,course, you are right in that some programs don't like alt ports (or more directly, some *clients* don't like alt ports) but when it comes to remote admin of servers, I have no problem at all, and in fact wouldit
changing the default ports just to add that extra level of raising the fruit. (That's not a Navy term, Jim!)
T
----- Original Message ----- From: Ball, Dan
To: [ISAserver.org Discussion List]
Sent: Wednesday, April 13, 2005 5:17 PM
Subject: [isalist] RE: Terminal Service Port Change?
http://www.ISAserver.org
Yep, goes back to the same old argument, do you hide the port to makeknown
harder to find, or just rely upon the security in place to make ahttp://www.webelists.com/cgi/lyris.pl?enter=isalistport safe? I prefer to leave "most" things at their default port, makes it easier for me to do my job, some programs don't like using alternate ports.
From: Greg Mulholland [mailto:greg@xxxxxxxxxxxxxx] Sent: Wednesday, April 13, 2005 18:12 To: [ISAserver.org Discussion List] Subject: [isalist] RE: Terminal Service Port Change?
http://www.ISAserver.org True, but if your going to leave rdp unprotected, or anything for that matter, we'll find it.. no matter what port you hide it on. ------------------------------------------------------ List Archives: http://www.webelists.com/cgi/lyris.pl?enter=isalist ISA Server Newsletter: http://www.isaserver.org/pages/newsletter.asp ISA Server FAQ: http://www.isaserver.org/pages/larticle.asp?type=FAQ ------------------------------------------------------ Other Internet Software Marketing Sites: World of Windows Networking: http://www.windowsnetworking.com Leading Network Software Directory: http://www.serverfiles.com No.1 Exchange Server Resource Site: http://www.msexchange.org Windows Security Resource Site: http://www.windowsecurity.com/ Network Security Library: http://www.secinf.net/ Windows 2000/NT Fax Solutions: http://www.ntfaxfaq.com ------------------------------------------------------ You are currently subscribed to this ISAserver.org Discussion List as: thor@xxxxxxxxxxxxxxx To unsubscribe visithttp://www.webelists.com/cgi/lyris.pl?enter=isalistReport abuse to listadmin@xxxxxxxxxxxxx
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