Researcher releases proof-of-concept VoIP hack

TechWorld.com - An expert has released a proof-of-concept program to show how easy it would be for criminals to eavesdrop on the VoIP-based phone calls of any company using the technology.

Called SIPtap, the software is able to monitor multiple voice-over-IP call streams, listening in and recording them for remote inspection as .wav files. All that the criminal would need to do would be to infect a single PC inside the network with a Trojan incorporating these functions, although the hack would work at the Internet service provider level as well.

The program can index "IP-tapped" calls by caller -- using Session Initiation Protocol identity information -- and by recipient, or even by date. Running from August this year until the most recent tap on Nov. 21, SIPtap had no problem extracting enough information on the test network to prove that recording of any and every VoIP call at a hypothetical company is now a trivial exercise.

SIPtap demonstrates that the worst-case nightmares of VoIP vulnerability are now well within the capabilities of organized crime, which could use such a program to steal confidential data from companies, governments and even the police.

The program is the work of U.K.-based VoIP expert Peter Cox, who co-founded and served as chief technology officer at firewall vendor BorderWare Technologies Inc. Cox left the company last summer to start his own VoIP consultancy, which is expected to be up and running by next spring. He was inspired to write the software after conversations with encryption guru Phil Zimmermann, creator of Zfone; Zfone was designed to protect against SIPtap-like hacking by using VoIP call encryption.

"We are in the early days of VoIP, but there is a knowledge gap," said Cox, lamenting that the mostly telecommunications-oriented engineers building such systems are naive when it comes to VoIP's inherent security weaknesses. "Companies using VoIP internally think they are protected.

"The threat is that an attacker engineers a Trojan and has it sit there passively [on a network], recording calls from anywhere on the Internet," Cox added.

His advice is simple: "Apply the same vigor when building a VoIP network you would when building a Web site."

Cox is currently running a series of workshops on VoIP threats in conjunction with SIP Services Europe.

Reprinted with permission from

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