Re: Some new SSH exploit script?

["R. DuFresne" <dufresne () sysinfo com>]

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All this is fine when services like ssh are only allowed for admins needing 
access to the systems behind the perimeter, or a very small userbase.  But 
when that user base is  large, and might well involve various vendor 
clients as well, it can be a pain in the butt to maintain and disseminate. 
And over time erodes into a broadly know value for you network as folks 
move on and vendors come and go and such, thus again perhaps lowering the 
bar and hanging fruit.  So for those small sites or sites only allowing 
ssh in for specific persons such as a few admin and perhaps a few 
application maintainers, and even a vendor or two, we find it easier to 
maintain the standard port and restrict access in the firewall and tcpd to 
specific addresses, and on occasion users via sshd_config settings as 
well.

Log cruft is a pretty lame reason and rational for making a choice to 
implement a non-standard port setting, admins should have the skills to 
filter and parse logs in a manner such that the cruft does not interfere 
with their daily log monitoring chores, else they have likely a lot of 
other cruft that must as well be driving them to near madness as well not 
relating to sshd and the kiddie brute-forcing tool of the week.

Application specific communication channels can be a different matter, as 
long as all non-standard settings are well documented for those that share 
in the maintenance or come after you can get into the work and fix flow at 
a running start.

Of course, alot of this depends upon how many twists and turns one feels is 
comfortable to make to get simple tasks and chores done, a matter of taste 
in some environs and a pain in the backside in larger or less technically 
minded envs.  Log cruft is something that knowledged admins have to deal 
with no matter what though and is not a valid rationale to the case in 
this arena, in my mind anyways.

Thanks,

Ron DuFresne


On Wed, 7 Jun 2006, Thor (Hammer of God) wrote:

> > Changing the port number, is akin, to hiding the door, because your
> > afraid of the lock installed in it. It only raises the bar to the
> > special olympics level.
> >
> > I believe in security in-depth, but this depth is so superficial, I
> > really don't think it's worth it.
>
> No, it's akin to hiding the door in _addition_ to having strong locks on it.
> This subject comes up here from time to time, and it basically always comes
> down to someone saying "it's so trivial that it doesn't matter" and others
> saying "if it helps at all, even if only slightly, then it's a good thing."
>
> I number myself among the latter group- if it raises your fruit higher than
> the guy next to you, then go for it.  Changing default listening ports
> immediately obviates you from standard/worm/kiddie traffic.  That, in itself
> is a good enough reason for me.
>
> We had this discussion over on the ISA list about RDP several months back.
> After that thread, I hosted terminal services and SQL on 2 boxes: one on
> 3389/1433, the other on 53343/43343 respectively for Feb, March and part of
> April.  There were something like 45,000 failed RDP logon attemps on 3389,
> and not a single logon attempt (other than from me) on 53343.  The SQL
> numbers were almost 200,000 on 1433, and something like 10 on 43343.  I was
> actually pretty surprised to see the 10.  (I've got the actual numbers on
> the box itself, I might bring it up and get the actual figures if I get
> time).
>
> You can speculate about port-scanning worms, "intelligent" viruses, etc all
> you want, but they're just not being written (yet).  Moving my RDP listener
> to 53343 prevented over 45,000 logon attempts.  To me, that is not a
> superficial security-in-depth mechanism.  There are a million different
> things that *could* have been done, but they just weren't.
>
> I'll continue to host RDP on an alternate port because it provides some
> value, albeit small, to my security in depth strategy.
>
> I also continue to find value in "source port" firewall rules where only
> connections to services initiated from a particular source port are allowed.
> Others have said that practice is also just "security through obscurity" yet
> I think it is a good idea, and it works for me.  I use this method to help
> protect access to my production servers for remote RDP access - RDP listens
> on an alternate port, and my ISA server only allows the connection when made
> from a specific source port (I actually use a small range of source ports) -
> there has never even been a connection attempt made (other than from me.)
>
> Given actual data I have collected, I'll continue to use this method as
> well.
>
>
>
> t
>
>
>
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you need to proactively protect your applications from hackers. Cenzic has the 
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