By Tim Greene
The threats against VoIP are numerous and seem to be growing, but in
2008 the technology probably won't suffer crippling attacks.
The potential danger is very real. VoIP is susceptible to the many
exploits that networks generally are heir to -- denial of service,
buffer overflows and more. VoIP PBXs are servers on corporate networks
and are only as secure as the networks themselves.
In addition, there are many voice-specific attacks and threats. These
have been chronicled by researchers and vendors intending to alert users
and suggest ways to guard against them.
For instance, two protocols widely used in VoIP -- H.323 and Inter
Asterisk eXchange -- have been shown to be vulnerable to sniffing during
authentication, which can reveal passwords that later can be used to
compromise the voice network. Implementations of Session Initiation
Protocol (SIP), an alternative VoIP protocol, can leave VoIP networks
open to unauthorized transport of data.
In addition, tools that can help find vulnerable deployments have been
published online by a VoIPSA, an industry group dedicated to securing
VoIP. The VoIPSA tools are intended to help businesses test and secure
their networks, but these and other online tools can be used to probe
for weaknesses as well.
Still, there have been few exploits so far and none that have been
widespread or crippling to businesses. "We are not hearing about
attacks. We dont think they are happening," says Lawrence Orans, an
analyst with Gartner.
Part of the reason may be that the largest VoIP vendors use proprietary
protocols, such as Cisco's Skinny, Nortel's Unistim and Avaya's variant
of H.323, Orans says. That makes them difficult to obtain and study for
potential security cracks. "These systems are not readily available to
the bad guys," he says.
SIP, which is gaining popularity, is a mixed bag, Orans says, because it
is readily available to those who might want to exploit it. "I would say
that SIP is a good-news, bad-news story. It's easy to get your hands on,
and that includes the bad guys. The good news is there are more options
to protect SIP," he says. These options include firewalls and
intrusion-prevention systems that support SIP (compare products).
Another reason for the lack of broad exploits is that there isnt enough
ROI for attackers' development time. Attackers' motivation may improve,
however, as VoIP increases in popularity, something it is doing
Hybrid PBX systems -- which handle both VoIP and TDM voice -- account
for 64% of all PBX lines sold, according to a December 2007 Infonetics
report. Pure IP systems (compare products) account for another 18%.
Meanwhile, not everybody agrees with the assessment that VoIP will not
suffer a major hit in 2008. "VoIP is, in essence, a time bomb, poised
for a massive exploit," says Paul Simmonds, a member of the management
board of the Jericho Forum, a user group promoting new principles for
All contents copyright 1995-2007 Network World, Inc.
Visit InfoSec News