Building The Net

Amazon Brute Force SIP Attacks – Dave Michels Interviews Me.

Shortly After my “SIP Brute Force Attack Originating From Amazon EC2 Hosts” post, Dave Michels interviewed me for an article Dark Side of the Cloud. This is that interview:

Dave:   What do you believe the intent was of the attacks? Free long distance?

Stu: Certainly free long distance would be one reason… But there are many other reasons to hijack a SIP account. I’m sure that organized crime would pay for a block of active SIP logins. They could use them to circumvent surveillance, or possibly use them for fraudulent boiler room calls about extended warranties and such.

Remember, most folks still believe that the Telephone System is secure… They tend to believe someone who is calling them.

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SIP Brute Force Attack Originating From Amazon EC2 Hosts.

I woke up Saturday morning to find strangely high network activity on some of our inbound connections. After a quick review, it turned out that most of the traffic was going into several of our hosted PBX systems. After a little more digging, I discovered that several systems on the Amazon EC2 network were preforming brute force attacks, against our VoIP servers. They were attempting to guess user names and passwords for our SIP clients. I immediately blocked all traffic from the attacking IPs and examined the logs. Thankfully, I found that non of the attacks had succeeded in guessing passwords.

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