RE: Terminal Service Port Change?

From: "Thor \(Hammer of God\)" <thor@xxxxxxxxxxxxxxx>
To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx>
Date: Thu, 14 Apr 2005 08:01:20 -0700

Somehow, I knew you'd say that ;)

----- Original Message ----- From: "Jim Harrison" <Jim@xxxxxxxxxxxx> To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx> Sent: Thursday, April 14, 2005 7:16 AM Subject: [isalist] RE: Terminal Service Port Change?

http://www.ISAserver.org

Red on both counts, of course...
:-)

-----Original Message-----
From: Thor (Hammer of God) [mailto:thor@xxxxxxxxxxxxxxx]
Sent: Wednesday, April 13, 2005 11:26 PM
To: [ISAserver.org Discussion List]
Subject: [isalist] RE: Terminal Service Port Change?

http://www.ISAserver.org

Damn you Harrison!!  How could you have known that!?!  And how did you
know
what the source port had to be for the allow rule???

"The force is strong with this one."

I have only two questions for you now:

1) Rare or Medium Rare?
2) Redhead, or Redhead?

----- Original Message ----- From: "Jim Harrison" <Jim@xxxxxxxxxxxx> To: "[ISAserver.org Discussion List]" <isalist@xxxxxxxxxxxxx> Sent: Wednesday, April 13, 2005 10:09 PM Subject: [isalist] RE: Terminal Service Port Change?

http://www.ISAserver.org

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!
-------------------------------------------------------


-----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

----- 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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