I am interested in 'fingerprinting' various SIP scanner attacks and using them to intelligently block attacks, rather than just blindly black listing any SIP message to a honey pot.

Additionally I think it would be wise to detect these missing ACKs and/or incomplete transactions from a legitimately mis-configured or malfunctioning end point, to help protect the core network from needless re-transmissions.

Having checked the Asterisk logs, this is what I'm looking to block if a certain threshold is exceeded-

[2016-04-05 13:10:52] WARNING[2010] chan_sip.c: Retransmission timeout reached on transmission eff430b8c1b6d21c2058049f41a7ec57 for seqno 1 (Critical Response)

Thanks

On Tue, Apr 5, 2016 at 1:14 PM, Daniel Tryba <d.tryba@pocos.nl> wrote:

On Tue, Apr 05, 2016 at 12:09:29AM +0100, Marrold wrote:
> I have been running a couple of Asterisk honey pots to get a better
> understanding of the tools and methods potential hackers are using to
> exploit SIP servers.
>
> I have observed many attacks from the 'sipcli' user agent that don't send
> ACKs.
[...]
> Please could anyone point me in the right direction to detect these non
> completed calls with a missing ACK in Kamailio? I am unsure on the
> terminology I should be using to search the online documentation.

Why do you care? The attacker doesn't care about receiving SIP messages,
they are only interested in initiating a call to a target, if the target
gets dialled you will be abused, by either an other source with a fully
function SIP stack or just something that might be spoofed.

What I do is blacklist addresses that send any SIP messages to my
honeypots, might be dangerous since with UDP anything can be spoofed (so
better make sure you have a whitelist and there is no connection between
the honeypots and your client facing SIP platform)

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