[SR-Users] dictionary attacks

[Uriel Rozenbaum]

Juha,

I think we should be specially careful about black-lists. We receive
many of these attacks in a per-day basis and a lot of them are from
residential addresses or university, so I'm guessing some kind of worm
or trojan performing the attack from various IPs.

If you have the time, try fail2ban deamon. It can relate some
brute-force events and act accordingly blocking an IP on iptables,
executing a script. You send to "jail" those addresses for a period of
time, then you can get them out again; and of course you can manually
revert.

Last, as a description of the attacks I saw, first it runs an NMAP
like scan checking which IPs answer from 5060, then it starts sending
registers (usually asterisk answers 404 if the user does not exist),
then when the proxy challenges, it interprets the user is found and
starts making dictionary attacks on the password (1234, admin, and so
on). Keep safe complicated passwords, make kamailio challenge
everything and you'll be safe. and again, fail2ban is a pretty good
solution for brute force.

This might help you finding a solution for your attacks.

Cheers,
Uriel

On Sun, Oct 24, 2010 at 8:54 AM, Juha Heinanen <jh at tutpro.com> wrote:
> while doing some tests, i noticed that one of my proxies started to
> receive lots of register requests with different user names starting
> from a letter.  there was also invite attempts in the logs.  they came
> from ip 202.82.16.99 which according to traceroute is somewhere in
> china.
>
> should we start publishing a black list of these attack ip addresses?
>
> -- juha
>
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