LAS VEGAS—During the Cold War, Soviet spies were able to monitor the US Embassy in Moscow by using a radioretroreflector bug—a device powered, like modern RFID tags, by a directed radio signal. But that was too old school for Ang Cui, a security researcher at Red Balloon Security and PhD candidate at Columbia University. He wanted to see if he could do all of that with software.
Building on a long history of research into TEMPEST emanations—the accidental radio signals given off by computing systems’ electrical components—Cui set out to create intentional radio signals that could be used as a carrier to broadcast data to an attacker even in situations where networks were “air-gapped” from the outside world. The result of the work of his research team is Funtenna, a software exploit he demonstrated at Black Hat today that can turn a device with embedded computing power into a radio-based backchannel to broadcast data to an attacker without using Wi-Fi, Bluetooth, or other known (and monitored) wireless communications channels.
Cui has previously demonstrated a number of ways to exploit embedded systems, including printers and voice-over-IP phones. In 2012, he demonstrated an exploit of Cisco phones that turned on the microphone and transformed phones into a remote listening device. Michael Ossmann of Great Scott Gadgets, a hardware hacker who has done some development of exploits based on concepts from the NSA's surveillance "playset," suggested to Cui that he could turn the handset cord of the phone into a “funtenna”—an improvised broadcast antenna generating radio frequency signals programmatically.