Re: Some new SSH exploit script?

From: Christine Kronberg (seeker@shalla.de)
Date: Tue Jun 06 2006 - 04:36:09 EDT


On Mon, 5 Jun 2006, Michael Sierchio wrote:
> Morning Wood wrote:
>>
>> > I beg to differ with you -- running a standard service on a non-standard
>> > port is a bid for security through obscurity.
>>
>> This wasnt implied as a full stop measure, but security through obscurity
>> coupled with other protections can enhance the overal security posture.
>> ( not to mention stopping 99.9% of unauthorized traffic )
>
> I don't see what the net effect is. You'll still see unauthorized connection

   The net effect is (currently) that this silly attempts are no longer
   spoiling the logfiles. On one host I moved my sshd to some other port
   as well. Not because of security concerns but simply to better view my
   log entries.

> attempts by ankle-biters on port 22. If your implementation is vulnerable,

   A syn coming in getting an rst. End of connection. From a single syn
   I cannot tell if it is authorized or not unless I specify network ranges
   that are allowed to get to my node on that port. In this case the other
   side gets a port unreachable or nothing at all depending on how I restrict
   access. A single syn doesn't worry me. An endless chain of syns to a
   specific port will raise questions directed to the location the syns
   originate from. But honestly, this only happens on rare occasions.

> running a service on a non-standard port offers little-to-no protection.

   Definitely. Being vulnerable is being vulnerable on any port you place
   an application.

> The number of TCP ports is very small, and the number of potential source
> computers for a lazy and quiet scan to determine what service you're
> running SSHD on is large. Are you going to change the service port on
> a daily basis? Hourly?

   For what? It's not necessary. Since the day I moved the port I just
   saw one single attempt to connect to that host on that port, which does
   not belong to the allowed ones. And that one checked it for being a web-
   server.
   Of course, things may/will chance over time.

   Cheers,

   Chris Kronberg.

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