No, it's not an April Fool's joke. If only it were…
Imagine you're a lawyer working on an important legal brief for a client at a coffee shop, airport or other public location. Unknown to you, your legal opponent is sitting on the other side of the room. Using an oscilloscope and an inexpensive wireless antenna, he sits down at his own laptop, and activates monitoring software. Thanks to a tiny antenna between your keyboard and the computer processor, your adversary can read everything you're typing into your laptop, with up to 95% accuracy, more than 60 feet away.
Even encrypted wireless keyboards are vulnerable, because each key still gives off a unique electromagnetic signal, which can be picked up with an antenna.
If that's not bad enough, if you're in the line of sight of your adversary—even hundreds of feet away—he can aim a laser microphone at your laptop to read what you've written. Using the laser's precise rendering of the vibrations your keystrokes leave on the screen, he can monitor what you've typed.
An attacker can pull off the same exploit, with similar results, on your home or office PC. It's even easier, in fact, because desktop monitors are larger. Plus, if you use an older PS/2 keyboard, hackers can pull the same information out of a nearby power socket.
Defense researchers have know for more than 50 years that it's possible to recover data from "leaks" in electronic equipment. Most of their research—which at one time was code-named "Tempest"—is still classified. But in the meantime, civilian researchers have discovered numerous ways to recover data using off-the-shelf components. Indeed, the laptop keyboard sniffer I just described can be constructed for less than US$5,000.
How can you protect yourself? The most basic precaution is to not use a PS/2 keyboard. Beyond that, you can purchase a "Tempest" laptop or PC certified to meet military standards. They cost considerably more than ordinary PCs, but if you believe someone might target you for this attack, they're worth every penny. Search the Internet for "Tempest laptop" or "tempest PC" to find suppliers.
Copyright © 2009 by Mark Nestmann
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