Lamphone: how can a light bulb spy on you?


Can a light bulb spy on you? Can you believe if I said that it was true?

In a research paper published this week, Ben Nassi, Yaron Pirutin, Adi Shamir, Yuval Elovici and Boris Zadov, researchers at Israel’s Ben-Gurion University of the Negev and the Weizmann Institute of Science, announced the development of a new spying technique which they call “Lamphone” that allows to get all sounds emitted in a remotely located room, as long as it is illuminated.

What is Lamphone?

Lamphone is based on the principle that objects vibrate when the sound wave hits their surface. When this happens in a light bulb, academics say the vibrations also create small flickers in the light emissions. By using powerful sensors, they can record changes in light and reverse the sound waves that hit the bulb’s surface.

This technique would allow anyone with a laptop, a telescope and an electro-optical sensor (worth a few hundred dollars) to listen, in real-time, to all the sounds emitted in a remotely located room, as long as it is illuminated.

So now you understand how can a light bulb spy on you

Limitations of Lamphone

Like any surveillance technique, Lamphone has its advantages and limitations.

The most obvious is that attackers need a direct line of sight to the bulb in a room or public space. Bulbs protected by lampshades are safe from this attack, as are conversations that take place in windowless rooms.

However, once an attacker has a line of sight on a light bulb, academics say that an attacker can use tools such as a telescope and an electro-optical sensor to record changes in the light in the bulb. This capture is possible at a distance and does not require being close to the target.

In experiments conducted for their research, they reported being able to pick up sounds and conversations from a distance of 25 meters.

In 2014, researchers at the Massachusetts Institute of Technology (MIT), Microsoft and Adobe developed a “visual microphone”. By analyzing a video recorded by a telescope of an object that picks up vibrations – a bag of chips or a houseplant, for example – they were able to reconstruct speech and music.

One of the group’s researchers, Yuval Elovici, has also been working on the hack brightness technique, which makes it possible to capture in a video the changes in brightness of LCD screens that are imperceptible to the naked eye, making it possible to steal documents and files from unconnected computers. However practical it may be, this “visual microphone” does not allow for urgent action, the Israeli researchers note. The same goes for the hack brightness.

The Lamphone, on the other hand, allows real-time espionage. “When you use it in real time, you can react immediately rather than lose the opportunity to intervene,” says Nassi. He also adds that the goal of this research is “ to make people aware of this type of attack“.

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