Lamphone attack can help spies just by observing a light bulb hanging in the room


Spies can hear your conversations just by observing a light bulb hanging in the room

Researchers here have found something that would be unbelievable to you, but it’s possible to spy on secret conversations happening in a room from a nearby remote location just by observing a light bulb hanging in the room that is visible from a window and calculating the amount of light it emits.

A team from the Israeli’s Ben-Gurion University of the Negev and the Weizmann Institute of Science published in a new paper about the discovery of the attack and it will also be presented at the Black Hat USA 2020 conference later this August. The team has developed a novel side-channel attacking technique that can be applied by eavesdroppers to recover full sound from a target room that contains an overhead hanging bulb.

The central premise of Lamphone hinges on detecting vibrations from hanging bulbs as a result of air pressure fluctuations that occur naturally when sound waves hit their surfaces and measuring the tiny changes in the bulb’s output that those small vibrations trigger to pick up snippets of conversations and identify music. The new approach is effective from great distances starting with at least 25 meters away from the target using a telescope.

We assume a victim located inside a room/office that contains a hanging light bulb. We consider an eavesdropper a malicious entity that is interested in spying on the victim in order to capture the victim’s conversations and make use of the information provided in the conversation (e.g., stealing the victim’s credit card number, performing extortion based on private information revealed by the victim, etc.).

the researchers said

The equipment needed to execute this attack is a telescope to provide a close-up view of the room containing the bulb from a distance, an electro-optical sensor that’s mounted on the telescope to convert light into an electrical current, an analog-to-digital converter to transform the sensor output to a digital signal, and a laptop to process incoming optical signals and output the recovered sound data.

We show how fluctuations in the air pressure on the surface of the hanging bulb (in response to sound), which cause the bulb to vibrate very slightly (a millidegree vibration), can be exploited by eavesdroppers to recover speech and singing, passively, externally, and in real-time. We analyze a hanging bulb’s response to sound via an electro-optical sensor and learn how to isolate the audio signal from the optical signal. Based on our analysis, we develop an algorithm to recover sound from the optical measurements obtained from the vibrations of a light bulb and captured by the electro-optical sensor.

the researchers added

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