[j-nsp] SSH_Brute_Force events

[Jonathan Lassoff]

On Thu, Apr 5, 2012 at 3:09 PM, Harri Makela <harri_makela at yahoo.com> wrote:
> Hi Guys
>
> We are getting "SSH_Brute_Force" alerts quite often from our Intrusion prevention systems (IPS) - ISS GX.
>
> Issue Description: We have detected SSH_Brute_Force events sourcing from external IP x.x.x.x targeting multiple internal IPs. This is probably an attempt to gain access to SSH enabled servers.
>
> What could be best practices to handle these alerts ? i.e.
>
> change SSH port  system wide from 22 to 10022 ?
> Report the ISP to contact with the customer which is really not a practical solution ?
>
> Any advice will be highly appreciated. I myself new to this and trying to document the process.

This is a very common occurrence on the open internet. Usually, these
remote hosts test out some common account names and passwords, looking
for weakly-protected accounts.

The first thing I would do to mitigate this risk in my network would
be to setup firewall filters (in the case of JunOS) on my loopback and
management interfaces so that only internal management stations (that
also cannot be reached from the open internet!) can reach the SSH
daemons on my router.

Switching SSH ports to a non-standard port will stop the casual
scanner, but doesn't really do anything to mitigate the risk.

--j