[AusNOG] VoIP Hack Attempts

[Mark Smith]

On Tue, 28 Sep 2010 00:13:57 +1000
Skeeve Stevens <Skeeve at eintellego.net> wrote:

> Hey all,
> 
> I've got a few customers who have noticed a large recent jump in SIP scans against their networks.
> 
> Null routing helps the response but doesn't stop the registration initiation - loading up servers with registrations.
> 
> This is easy to stop on closed VoIP systems, but not on hosted Voice platforms which users come from other ISP's/networks, this seems to be very difficult.
> 
> Does anyone have any ideas - we are fresh out at the moment, apart from beefing up security on the VoIP servers themselves using fail2ban or other things that detect rapid registrations and then firewalls them.
> 
> Having a normal server hacked is one thing but VoIP hacking has taken on a new intensity as the hackers can make a LARGE amount of money by comprising a VoIP system.
> 
> Recently, we've been brought in to clean up the mess in several incidents where a couple of VoIP systems have been compromised in incidents totalling over AU$100,000.
> 
> And the carriers are rarely sympathetic.
> 
> If it isn't obvious as to how/why they're doing this - the hackers get in, open a SIP account so their VoIP system can register, and then they channel certain calls via the comprised system.  This has the effect of them charging the end user and making money, while not paying for the calls to be delivered to the destination.
> 
> Advice:
> 
> -          Block destinations to obscure places that your customers are unlikely to call, and only unblock them if they request
> 
> -          Watch billing to certain locations and if there is a massive jump, do something
> 
> -          Watch your customers and if their billing jumps by a massive amount, alert them as fast as you can - or you just might be liable
> 

These last couple seem to be a pretty good idea even without this
specific issue. It's pretty much what credit card companies are doing
these days. "sip anomaly detection" in google turned up a few links
that look interesting.

> ...Skeeve
> 
> --
> Skeeve Stevens, CEO
> eintellego Pty Ltd - The Networking Specialists
> skeeve at eintellego.net / www.eintellego.net
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> Cell +61 (0)414 753 383 / skype://skeeve
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