Recently published research papers, academic researchers introduced in detail the new technology of restoring sound waves (voices, dialogues and songs) in a room 25 meters away by observing the vibration of the bulb and recording the light changes of the bulb.
Researchers call it a light bulb receiver ( Lamphone), using the principle that objects vibrate when sound waves hit the surface of the object. When this happens to light bulbs, academic researchers say that vibrations can also cause tiny flickers when the light bulb glows. They further pointed out that by using powerful sensors to record changes in light, and reverse analysis to get the sound waves hitting the bulb surface.
But like any new surveillance technology, bulb handsets have advantages and limitations. The most obvious disadvantage is that the eavesdropper needs to aim at the light bulb in the room or public place. Therefore, using a lampshade to cover the bulb can avoid this attack, and talk in a room with no windows will not be eavesdropped by Lamphone technology.
However, once the bulb is in sight, malicious attackers can use tools such as telescopes and photoelectric sensors to record the light changes of the bulb from a long distance. The entire attack does not need to be very close to the target. To. Paper factsIn particular, the experience pointed out that they successfully restored the voice and dialogue from 25 meters away.
"The use of larger telescopes and more powerful sensor equipment can also expand the monitoring range." The research team said. In their experiment, the research team stated that it can successfully restore human voices and even have spatial reverberations such as music playing in the background.
Another disadvantage is that the volume must be loud enough to generate vibration, or the speaker must be close enough to the bulb. But no matter what, only a telescope and a video recorder can eavesdrop in an office tens of meters away by a window in a corner. This is undoubtedly a great achievement. For many companies, this is a more dangerous situation. .
But the bulb receiver is not a unique new eavesdropping technology. There are other similar attack methods in the industry. In the past, other eavesdropping techniques, such as those published by the USENIX Advanced Computing System Association, canThe signal of the internal gyroscope is restored to voice, and the visual microphone developed by the Massachusetts Institute of Technology (MIT) can restore passive sound through video files.
Nevertheless, the research team stated that the bulb handset has advantages over the above attacks. First, because it is passive, it does not require malware to be implanted in the victim’s device in advance, and it can operate in real time. And it does not require a lot of computing resources to process data.
The research team pointed out that the attacker only needs a laptop to process the bulb receiver data, which allows the attacker to use the bulb receiver to track conversations in real time. Another disadvantage is that the attack is not applicable to all types of light bulbs, so the result of the attack will depend on the brand, model, and product technical specifications of the light bulb, such as glass thickness or brightness, wattage, and lumen.