Malware Turns Computers Into Cellular Antenna

A team of Israeli researchers have improved on a way to steal data from air-gapped computers, thought to be safer from attack due to their isolation from the Internet.

They’ve figured out how to turn the computer into a cellular transmitter, leaking bits of data that can be picked up by a nearby low-end mobile phone.

While other research has shown it possible to steal data this way, some of those methods required some hardware modifications to the computer. This attack uses ordinary computer hardware to send out the cellular signals.

Their research, which will be featured next week at the 24th USENIX Security Symposium in Washington, D.C., is the first to show it’s possible to steal data using just specialized malware on the computer and the mobile phone.

“If somebody wanted to get access to somebody’s computer at home — let’s say the computer at home wasn’t per se connected to the Internet — you could possibly receive the signal from outside the person’s house,” said Yisroel Mirsky, a doctoral student at Ben-Gurion University and study co-author.

The air-gapped computer that is targeted does need to have a malware program developed by the researchers installed. That could be accomplished by creating a type of worm that infects a machine when a removable drive is connected. It’s believed this method was used to deliver Stuxnet, the malware that sabotaged Iran’s uranium centrifuges.

The malware, called GSMem, acts as a transmitter on an infected computer. It creates specific, memory-related instructions that are transmitted between a computer’s CPU and memory, generating radio waves at GSM, UMTS and LTE frequencies that can be picked up by a nearby mobile device.

The GSMem component that runs on a computer is tiny. “Because our malware has such a small footprint in the memory, it would be very difficult and can easily evade detection,” said Mordechai Guri, also a doctoral student at Ben-Gurion.

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