Penetration Testing mailing list archives

Re: Some new SSH exploit script?


From: "Adam.Chesnutt" <icetre () digitalfreezer net>
Date: Wed, 07 Jun 2006 10:57:22 -0400

silentw wrote:
Running a service on a non-standard port yields zero increase in
security.  That was my point.

I completely disagree for several reasons.

There has been much talk about the number of connections on port 22.
thousands of random connections that just waste your time. If you dont
have a guessable password why do you care ? reasurces.

Yeah this is true.. But in effect it is minimal.

1) It wastes your resorces. If your logs arn't full of usless crap you
have more time, more money, more hardware that you can better spend
elseware on things that will actually help you.
Grep? The overall volume of logs is greater, but it's easy to parse hacktards out of your logs.

2) Security through obscurity is a legitimate part of defense in
depth. (in this case) If you keep your services up to date, a
non-standard port could save you from a 0day attack / worm / n00b.
that is an increase in security.

Um, no

SSH is so easy to detect, that most automated tools would find it on a nonstandard port with minimal effort. However, nonstandard ports would most likely nail out worms, but 0-day owners have better sk1llz and t00lz, and n00bs wouldn't know what to do if your server was properly patched/secured anyways.

It really (for me, anyway) comes down to reasources - if you can cut
the junk in your logs by 90% just by changing a port, it is worth
considering. Anyone who has working in a large environment will know
exactly what I mean.


I've worked in several ISPs, and to tell you the truth, I'd much rather have easily greppable logs, that still contain the attempts. This falls under the paradigm of keeping your enemy close. I know who and what they are, and by correlating the attempts, I usually have a pretty good idea of the skill level I'm dealing with.

If you have a problem with an overwhelming amount of incoming security events, try correlation engines such as Neusecure or netForensics.

While I agree, it makes the logs more readable, the cost is making your logs less effective at their job.

Really the solution here, is to have confidence in your security measures. Remember, 0-day is just the tip of the iceberg, don't forget about private exploits. You have to remember, if someone wants to own you, you will be owned. There's always some oversight, there's always some attack vector. The whole point is raising the bar.

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.

Firewall the port after 5 bad attempts, it's a trivial script to write.

Adam



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