VoIPowering Your Office: The Thorny VoIP Security Thicket

Security for Internet-based IP communications is a problem that isn’t going
to go away. Not only do we have to protect ourselves from snoopy network administrators,
snoopy competitors, snoopy marketers, and organized crime, but our own governments
are engaged in a relentless assault on our remaining shreds of privacy. Throw
in a large helping of businesses whose inability to protect customer records
could fuel a 21st century Three Stooges revival, and a person might want to
give up and not even try, and just hurl her/himself naked into the universe.

But grumpy old codgers like me don’t give up that easily. VoIP suffers from
the same core weaknesses that afflict e-mail, Web sites, and all other services
that cross the Internet: The Internet was born in a more trusting era, and it
served a small set of professional and academic users who did not envision that
it would turn into the world’s largest shopping mall, the most crime-infested
neighborhood, and largest porn distributor. It has no built-in safety mechanisms
such as reliable audit trails, encryption, or tools for preventing unwanted
traffic from invading your network. And thus we have an incredibly polluted
Internet that excels at enabling international crime, aided and abetted by legions
of malware-friendly Windows PCs.

Perils everywhere

There are three types of technological threats: denial of service, SPIT (phone
spam), and eavesdropping. There are also social engineering threats, which are
probably more common and more successful. They don’t depend on fancy hacking skills,
but simply asking people for information. I don’t know how to implant reliable
baloney detectors in employees, so let’s take a look at technological threats.

Eavesdropping and snooping

If you’ve ever worked in IT, you know that an awful lot of unauthorized and unethical
snooping goes on all the way along the chain—in your own business, at your ISP,
and at all stops between endpoints. A percentage of IT staff are known for snooping
on network traffic. They’re reading e-mail, monitoring Web surfing, and spying
on instant messaging. Records clerks, mail clerks, and other administrative staff
have access to everything. It’s always amazed me how this obvious security hole
is routinely overlooked, and companies that invest millions in futuristic electronic
card key systems, and biometrics, and mean-looking security cops are careless
about who they hire to manage their records. Usually the cheapest perma-temps
they can find. Combine this with government’s relentless drive to bug every law-abiding
citizen into oblivion, and it’s not a pretty sight.

Anyone with access to the wires carrying your voice and data traffic can eavesdrop
with trivial ease. There are powerful open-source encryption tools for e-mail
and Web traffic; I think we need something that works at the protocol level
for VoIP.

Skype uses reliable old AES and RSA-based key-pair encryption, which authenticates
and encrypts both ends of the call session. This works okay for a closed network,
but does no good out in the big bad world of untrusted, unknown people calling
you. It seems that something that operates similar to SSL on Web sites would
be a nice protection—only the server needs to be trusted, so any visitor
to an SSL-enabled site receives the benefit of an encrypted session.

Since strong encryption really is strong and foils even government snoops, its days are probably numbered. So use it while you can.


“SPam over Internet Telephony” has not become a serious problem yet. But it seems
a safe prediction that it will be, given the utter lack of conscience demonstrated
by spammers and their idiot cousins, “legitimate” marketers. They already did
their best to ruin postal mail and old-fashioned telephone service, and nearly
plastered the entire United States with billboards until laws were passed to restrict
them. However, the tide is turning and science fiction is coming true—ads
infest everything, from buses to shopping carts to branded consumer goods of all
kinds, and TV commercials have escaped from program breaks and now intrude on

All of these things are self-limiting to a small degree because of the cost. But the same technologies that give us inexpensive, powerful telephony can also be exploited by vandals, I mean spammers/”legitimate” marketers. I doubt they will be deterred by infinitesimal rates of return any more than e-mail spammers are.

Denial of Service

This is the hardest to defend against. An attacker floods your network with packets
and overloads it. In this era of giant botnets fueled by idiotically non-securable
Windows PCs, an attack can come from a multitude of sources and be impossible
to trace to any origins. In some countries there are thriving extortion rackets
based on DoS attacks—pay up and the attack stops.

I wish I had some words of wisdom and good advice on how to deal with these
threats, but as far as I know strong encryption is the only reliable tool currently
available, and it only stops snooping. The rest is uncharted territory. You
can install the Snort intrusion detection system and monitor threats from the
Internet, and possibly get early warnings of problems. Work with service providers
who are connected to multiple Internet backbones, and who are experienced in
dealing with DoS and other Internet threats. Don’t give up your PSTN just yet—pure
VoIP is not good enough for mission-critical phone services. Visit the various
security sites and stay informed. At the least, you’ll learn warning signs and
won’t be taken by surprise if something bad happens.


Latest Articles

Follow Us On Social Media

Explore More