[ISN] Voice Over IP Can Be Vulnerable To Hackers, Too

[InfoSec News]

http://www.informationweek.com/story/showArticle.jhtml?articleID=20300851

By W. David Gardner
TechWeb News
May 13, 2004 

As voice over IP sweeps across the high-tech landscape, many IT
managers are being lulled into a dangerous complacency because they
look upon Internet phoning as a relatively secure technology--not as
an IP service susceptible to the same worms, viruses, and other
pestilence that threatens all networked systems.

"With VoIP," security specialist Mark Nagiel said Thursday in an
interview, "we're inserting a new technology into an unsecured and
unprotected environment. VoIP is essentially availability driven, not
security driven, and that's the problem." But Nagiel, manager of
security consulting at NEC Unified Solutions, said that there are
measures that can be taken to protect voice over IP from the threats
that confront Web telephoning.

The first step--an obvious one, he says--is to secure existing TCP/IP
networks. Nagiel is finding that the new government-required
regulations--such as Sarbanes-Oxley, which stipulates improved
accounting record-keeping, and HIPAA in health care--are helping IT
managers because they impose security discipline across-the-board.  
"The financial and health-care fields are getting secured very
quickly," Nagiel said.

Even so, there can be difficulties. He noted that although hospitals'
protection of patient records generally has been excellent, they often
neglect to completely secure physicians' conversations. Security
managers can overlook the fact that voice over IP conversations can
reside on servers that can be hacked.

The traditional voice model utilized PBXs, which were stable and
secure, Nagiel noted. If the voice over IP infrastructure isn't
properly protected, it can easily be hacked and recorded calls can be
eavesdropped. He says the networks utilized to transmit voice over
IP--routers, servers, and even switches--are more susceptible to
hacking than traditional telephony equipment.

It's also relatively easy to launch an attack against a voice over IP
network because the software tools available to hackers and others
bent on invading a network are more available and easier to use. "And
the exposure levels have gone up because there are so many nets," he
said.

What's the solution? "You need strong encryption over VoIP servers and
VoIP client devices," Nagiel said. He observed that extensive
encryption can slow down efficiency of networks, but encryption is a
small price to pay to avoid denial-of-service attacks and invasions of
networks. Another useful defense tactic is to use virtual LANs
"whenever possible to separate traffic," according to Nagiel. In this
way, transmitted data can be segregated into unique virtual LANs for
data and voice transmission.

However, Nagiel cautioned that security managers should resist using
shared Ethernet network segments for voice.