New Authentication Scheme Combats Keyloggers, Shoulder-Hacking

Researchers have built a prototype authentication technique that could ultimately reduce the risk of attackers hacking users' credentials via a keylogger or spyware.

The so-called Undercover system, which was built by Carnegie Mellon University faculty member Nicolas Christin and two CMU graduate students, approaches authentication differently: It hides the authentication challenges rather than the user's input or password during the authentication process.

The technique also can protect users from getting "shoulder-surfed" at the ATM machine while they type in their PIN, for instance, according to the researchers. "I am a bit nervous every time I withdraw money from an ATM," Christin said. "Crooks can see me type my 'secret' PIN and very easily figure out what it is, which becomes a big problem if they also gain access to my card number."

CMU CyLab's Undercover uses a combination of visual and tactile signals in the authentication process. It runs on a PC, which works with a trackball controlled by a Lego Mindstorm NXT robot. The trackball system and robot are combined in a plastic case that has numeric buttons for users to enter their answers to challenges they view on the PC monitor, as well as the trackball itself.

It works like this: The system displays a set of images to the user and asks if any belongs to the image portfolio that the user had previously selected. At the same time, the trackball sends the user a signal that maps each button on the case to a certain answer. The user's hand must cover the trackball for it to operate, so a sneaky observer wouldn't be able to see his or her selections, or answers.

So a would-be attacker can't "see" the tactile challenge presented by the trackball and therefore doesn't get the user's authentication data, even though he or she could see the image challenge on the display.

The CMU researchers tested the system as well as a pure PIN authentication solution on 38 users. The researchers were able to "hack" all of the traditional PINs. Only rarely were they able to correctly guess the solution to the Undercover challenge -- just in a few instances where the user's hand movements or comments gave them away somehow.

The researchers will present a paper on their research at an international human-computer interaction conference in Florence, Italy, in April.

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