WHAT IS IT?

 

The air around you is thick with electromagnetic radiation. It’s totally harmless at the level of concentration you’re used to—it takes a lot to beat up your genes enough for cancer or flipper babies to become an issue. But everything electronic you own puts out a signal, and that signal can be intercepted. With the right equipment and know-how, someone could be reading what’s on your computer screen right now.

This is called Van Eck phreaking. Phreaking is hacker slang for the signals intelligence (SigInt, if you want to sound like you read a lot of Tom Clancy novels) hobby some nerds acquired in the mid-eighties when they realized they could game the newly computerized telecommunications system with a sequence of tones or clicks. It’s evolved to refer to any hack that involves the interception or manipulation of a signal. Phone phreaking was used for low-level toll fraud. So far as anyone knows, Van Eck phreaking isn’t something done by civilians, except for engineers with something to prove.

To do it, you need to build a device that can intercept and interpret the electromagnetic signal broadcast by a computer monitor. For about $100, you can get a substandard picture and a twenty-to-forty-foot range; short, but enough for someone parked by the curb in front of your house. As you add cost and sophistication, you can increase the fidelity of the image and extend the range up to half a mile. Military-grade Van Eck interceptors can run into the hundreds of thousands of dollars, but you can build a very effective long-range interceptor for a little under $2,000.