atcomsystems.ca/forum Forums General Telecom News Hackers targeting VoIP systems.

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Good article, thanks for sharing.

In this case, it looks like they're not targeting VoIP systems, but are using VoIP systems to annoy their victims.

I really don't know how you can prevent this. Since it is easy to change outbound DID on most VoIP platforms, you couldn't block a certain CID, at least if the perpetrator is clever.

Actually your title is a bit misleading, It isn't targetting VoIP systems. They are using the anominity of VoIP to target any system.

If one could spoof enough numbers,had the bandwidth,and a dialer program, they could DoS virtually anyone. with a phone number.

Got a couple of POTS lines, make enough calls to busy out all the lines, got a PRI, all you need is 23 calls. The bigger the system the bigger attack but with the right software anything is possible.

What is scary is the fact that the initial caller addressed her by name.

I had a City actually experience this, I don't think it was a purposeful DoS but rather and inadvertant DoS from a robodialer getting caught up in the Auto Attendant.

I just encountered this yesterday with a customer that is a hospital. They were complaining of slow dial tone and incomplete calls. I looked at the system's activity log remotely and saw that all of their PRI trunks (46) were tied up, though most just said that there was a misc. tone on them.

I went to watch an on-the-fly SMDR stream and saw that there were about seven numbers from all over the country that were repeatedly dialing into three vacant DID numbers on our switch. Calls were coming in literally dozens at a time.

The customer tried getting Verizon to block the calls, but they weren't really interested in helping. They then added these numbers to the do not call registry. Lo and behold, the calls have now stopped and the system is functioning normally. I'm not sure if Verizon ended up doing something, the DNC registry worked or these people just got tired and found someone else to screw with.