Not so long ago, we wrote about methods that Mordechai Guri and his colleagues at Ben-Gurion University devised to extract information from a device that is not only not connected to the Internet, but also physically isolated from the network. At the Black Hat USA 2020 conference, another researcher from Ben-Gurion University presented a report on a related topic. Ben Nassi spoke about a visual eavesdropping method that he and his colleagues call Lamphone.
We’ll talk about how Lamphone works below, but let’s start with a short digression into the history of the issue.
How is it possible to see sound?
One well-known technology for remotely recording sound using so-called visual methods is the laser microphone. This technique is pretty straightforward.
The people wiretapping a conversation direct a laser beam operating in the infrared range (i.e., invisible to the human eye) at a suitable surface (typically window glass) in the room where the conversation is taking place. The beam reflects off the surface and hits the receiver. Sound waves create vibrations on the surface of the object, which in turn change the behavior of the reflected laser beam. The receiver records the changes, which are eventually converted into a sound recording of the conversation.
The technology has been in use since the Cold War era, and it has turned up in many spy films. You have probably seen it depicted in one of them. Several companies produce ready-made devices for laser eavesdropping, and their declared operating range extends to 500 or even 1,000 meters. For those worr ..
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