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Swiss boffins sniff passwords from (wired) keyboards 65 feet away

Electromagnetic eavesdropping, 007

Swiss researchers have demonstrated a variety of ways to eavesdrop on the sensitive messages computer users type by monitoring their wired keyboards. At least 11 models using a wide range of connection types are vulnerable.

The researchers from the Security and Cryptography Laboratory at Ecole Polytechnique Federale de Lausanne are able to capture keystrokes by monitoring the electromagnetic radiation of PS/2, universal serial bus, or laptop keyboards. They've outline four separate attack methods, some that work at a distance of as much as 65 feet from the target.

In one video demonstration, researchers Martin Vuagnoux and Sylvain Pasini sniff out the the keystrokes typed into a standard keyboard using a large antenna that's about 20 to 30 feet away in an adjacent room.

"We conclude that wired computer keyboards sold in the stores generate compromising emanations (mainly because of the cost pressures in the design)," they write here. "Hence they are not safe to transmit sensitive information."

No doubt, electromagnetic eavesdropping dates back to the mid 1980s, if not earlier. But Vuagnoux says many of today's keyboards have been adapted to prevent those attacks from working. The research shows that even these keyboards are vulnerable to electromagnetic sniffing.

The video demonstrations show a computer that reads input from antennas that monitor a specified frequency. In both cases, the computer was able to determine the keystrokes typed on keyboards connected to a laptop and power supply and LCD monitors were disconnected to prevent potential power transmissions or wireless communications. Vuagnous said in an email that the attacks would still work even if the power supplies and monitors were plugged in.

The demonstration has already gotten the attention of other security researchers.

"It's definitely believable that this is possible," Charlie Miller, principal security analyst for Independent Security Evaluators. "It is very James Bond."

The idea would be for an attacker to sniff passwords and other sensitive data using equipment located in an adjacent hotel room, office, or home.

Even still, it's easy to see the limitations of such attacks. Interference from other televisions, lights, or other devices seems likely, although the video demonstrations suggest that the attacks work even when there are nearby computer monitors. The other thing that makes the attack unfeasible is the amount of sophisticated equipment required. Given all the fuss and expense, why not just sneak a keylogger onto the target's machine?

The findings will be fleshed out in an upcoming research paper. ®

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