RE: Terminal Service Port Change?
- From: "Jim Harrison" <Jim@xxxxxxxxxxxx>
- To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx>
- Date: Wed, 13 Apr 2005 22:09:37 -0700
Nope - there are those who still believe that it's 42, but I have
incontrovertible (top fails to fold down) evidence that it's actually
43.
-----Original Message-----
From: Greg Mulholland [mailto:greg@xxxxxxxxxxxxxx]
Sent: Wednesday, April 13, 2005 9:36 PM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: Terminal Service Port Change?
http://www.ISAserver.org
It's a trick question! Its 3389 aint it :P
-----Original Message-----
From: Jim Harrison [mailto:Jim@xxxxxxxxxxxx]
Sent: Thursday, 14 April 2005 1:47 PM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: Terminal Service Port Change?
http://www.ISAserver.org
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!
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-----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?
> 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 be
it;
> but 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"
scanning
> and/or worm activity. Greg is absolutely correct in that obscuring a
> service via port change will not thwart a directed attack, but
security
> through obscurity does work as long as the target remains obscure.
RDP
>
> services on alt ports are difficult to detect unless you can hit the
box
>
> 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 null
sessions
> on
> weak Win2k installs).
>
> To speak to that old argument, I would say to do *both* if you can.
Of
> 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 would
recommend,
>
> 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 make
it
>
> harder to find, or just rely upon the security in place to make a
known
> port
> 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.
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