Have you dealt with a TDoS attack?

Telephony Denial of Service (TDoS) has gotten some recent press due to the National Cybersecurity & Communications Integration Center National Coordinating Center for Communications warning about the possibility of TDoS attacks targeting public telephone systems.

 

TDoS is a total flood of your legitimate service channel so it's difficult to defend against. Calls are delivered to you from a trusted service provider, unlike a DoS attack originated from the Internet.

 

In the SIP world the TDoS calls may have forged origination numbers, and be generated by a script running on a SIP proxy. The attacker actually uses a SIP trunk connected to a service provider. Calls may also come from multiple real numbers as part of a social media campaign or other traffic pumping scheme. The position taken by some vendors that sell TDoS prevention solutions that they can just tear down calls that match a signature based on origination number or even an audio sample. That's great, but a true TDoS is going to set up new calls as