Cisco Confirms Its VOIP Phones Spies On Remote Calls

Linda Leung

Cisco confirmed it is possible to eavesdrop on remote conversations using Cisco VoIP phones. In its security response, Cisco says: "an attacker with valid Extension Mobility authentication credentials could cause a Cisco Unified IP Phone configured to use the Extension Mobility feature to transmit or receive a Real-Time Transport Protocol (RTP) audio stream."

Cisco adds that Extension Mobility authentication credentials are not tied to individual IP phones and that "any Extension Mobility account configured on an IP phone's Cisco Unified Communications Manager/CallManager (CUCM) server can be used to perform an eavesdropping attack."

The technique was described by Telindus researcher Joffrey Czarny at HACK.LU 2007 in Luxembourg in October.

Cisco has published some workarounds to this problem in its security response.

Also in October, two security experts at hacker conference ToorCon9 in San Diego hacked into their hotel's corporate network using a Cisco VoIP phone.

The hackers, John Kindervag and Jason Ostrom said they were able to access the hotel's financial and corporate network and recorded other phone calls, according to a blog on Wired.com.

The hackers used penetration tests propounded by a tool called VoIP Hopper, which mimics the Cisco data packets sent at three minute intervals and then trades a new Ethernet interface, getting the PC - which the hackers switched in place of the hotel phone - into the network running the VoIP, according to the blog post.

The Avaya configuration is superior to Cisco, according to the hackers, because you have to send requests beyond a sniffer. Although it can be breached the same way, by replacing the phone with a PC.

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VOIP Tricks You Cant Wait To Try

The really nice thing about VOIP is that it is a service that you can take with you when you travel. For example, most hotels now have high-speed Internet service, and if you take your VOIP phone with you, you can plug in at the hotel and continue to make and receive calls at your regular phone number as if you had never left home. Keep in mind that if the hotel offers ONLY a wireless Internet connection, as many of them do as your only option, this presents another problem and you will need additional hardware to convert that wireless signal into an RJ45 jack that you can plug your VOIP DTA box into.

I know of one business person who does not leave home without his VOIP phone, it is always one of the first things that gets packed. So when he gets to his hotel in Chicago or New York or Denver or even Germany or Hong Kong, he plugs in his VOIP phone and is back to work. While it may seem strange to have a VOIP phone plugged into your Hong Kong hotel room, and have people call you on it by dialing an Orlando phone number (if you live in Orlando), that is how VOIP works and it really is nice.

Another thing you can do is say you have relatives in Europe or the UK that you like to talk to but it is prohibitively expensive to call overseas very often. To solve this problem, what you should do is get a VOIP phone for you, and have them get a VOIP phone from the same provider. Now even though they are living in London or Munich, they will have a Detroit or Houston phone number. They can call you and talk as long as you want, or you can call them on their assigned phone number (which might appear to be Detroit or Denver) and talk as long as you want. The only thing they need is that high-speed Internet connection, and of course an electrical adapter to accommodate the different voltages overseas.

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