Researchers at the Ruhr University in Bochum are able to track down hardware manipulation using radio waves. According to the experts, their specifically placed antennas react to even the smallest changes in the environment.
Test with two antennas
The researchers provide the system to be protected with two antennas: a transmitter and a receiver. The transmitter emits a special radio signal into the environment, which spreads throughout the system and bounces off walls and computer components. As a result of all these reflections, the receiver receives a signal that is as characteristic of the system as a fingerprint.
Tiny changes to the system are enough to affect the fingerprint. The IT experts equipped a conventional computer with radio antennas and drilled holes in the housing at regular intervals. Through these, they were able to insert a fine metal needle into the interior of the system and see if they noticed the change in the radio signal. They varied the thickness of the needle, the position and the depth of penetration.
With the computer running, the experts were able to reliably detect the penetration of a 0.3 millimeter thick needle from a penetration depth of one centimeter. Even with a needle 0.1 millimeters thick, the system still hit, but not in all positions. “The closer the needle is to the receiving antenna, the easier it is to detect. In practice, it makes sense to think carefully about where to place the antennas. They should be as close as possible to the components that are particularly worthy of protection,” says RUB researcher Johannes Tobisch.