Sniff This!!!

March 2009

Researchers sniff PC keyboard strokes from thin air. The PC keyboard an individual may be using could give away passwords. Researchers say they have discovered new ways to read what someone is typing by aiming special wireless or laser equipment at the keyboard or by simply plugging into a nearby electrical socket. Two separate research teams, from the Ecole Polytechnique Federale de Lausanne and security consultancy Inverse Path, have taken a close look at the electromagnetic radiation that is generated every time a computer keyboard is tapped. It turns out that this keystroke radiation is actually pretty easy to capture and decode, if someone is a computer hacker, that is. The Ecole Polytechnique team did its work over the air. Using an oscilloscope and an inexpensive wireless antenna, the team was able to pick up keystrokes from virtually any keyboard, including laptops. “We discovered four different ways to recover the keystroke of a keyboard,” said a Ph.D. student at the university. With the keyboard’s cabling and nearby power wires acting as antennas for these electromagnetic signals, the researchers were able to read keystrokes with 95 percent accuracy over a distance of up to 20 meters (22 yards), in ideal conditions. Laptops were the hardest to read, because the cable between the keyboard and the PC is so short, making for a tiny antenna. The researchers found a way to sniff USB keyboards, but older PS/2 keyboards, which have ground wires that connect right into the electric grid, were the best.