"These vampires are everywhere," he says. "Some are updating iTunes or streaming Pandora Radio, others are playing games or updating Facebook. The really scary ones are downloading media files and installing viruses. Not only are these people not doing their jobs, they're also slowing everyone else down. Then suddenly your IP phones stop working because somebody is downloading a BitTorrent."
Your best defense: Sunlight. The first step is to find out who's sucking up all the bandwidth and bring them into the light of day, says Melvin.
"These companies all have policies about what you can and can't do on their networks," he says. "The problem is they have no idea what people are actually doing, so the policies are completely unenforceable. Our solution is to bring these bandwidth vampires out into the sunlight and watch them melt."
Another option: Deploy software at the network gateway to dictate how much bandwidth each device will be allotted for YouTube, Facebook, and other nonbusiness applications, says Tim Naramore, CTO for Masergy, a provider of managed network services.
"To drive a stake through the heart of employee-owned devices you need to shift your network controls from the endpoints to the network," he says.
Like Keyboard Zombies, Ghosts in the Machine put sensitive corporate data at risk -- but these malicious insiders are doing it on purpose and often for a profit. There are also two kinds of ghosts, says Symantec's Matthews: one seeking revenge, the other looking for a payday.
"The first kind is usually a good employee who's been doing good work, only something happened at work that caused them to be disgruntled," says Matthews. "The other kind is the opportunist. He's looking to rip off a company's intellectual property to start his own company or sell it to your competitors."
With the collapse of the Soviet empire, many old-school spies are turning to corporate espionage and recruiting operatives inside U.S. companies, says Matthews.