Advanced espionage methods have evolved step by step over the years: listening devices connected to the phone line, hacked phones, insects on the wall; even laser bouncing off the window of a building and detecting conversations inside… now there is a new tool for voice spies: any lamp visible from the window of the room.
Researchers at Ben-Gurion University and the Weizmann Institute of Science in Israel have discovered a new method used in long-distance espionage, which they call the “lambaphone.” According to the scientists, anyone with a laptop and devices that cost less than a thousand dollars (just a telescope and a $ 400 electro-optical sensor) can instantly hear all the sounds coming out of a room 25 miles away. In addition, it can only do this by observing the small vibrations that these sounds create on the glass surface of the lamp inside. Researchers have shown that a spy can collect sounds that are clear enough to understand the content of the conversation and even recognize the music playing by measuring the small changes that these vibrations cause in the light coming out of the lamp.
“Any sound in the room can be listened to without hacking anything and without any devices in the room,” says Ben Nassi, a security researcher at Ben-Gurion University who developed this method with fellow researchers Yaron Pirutin and Boris Zadov. “All you have to do is see the dangling lamp.”
The findings, presented at the Black Hat Security Conference in August, researchers in their experiments as a destination of choice for 25 yards away from each telescope lens telescope array and the bureau planted a Thorlabs PDA100A2 electro-optical sensor placed in front of it. Then, using an analog-to-digital converter, they converted the electrical signals from this sensor into digital information. When they played music and audio recordings in a remote room, they sent the information collected by this device to a laptop computer, and the computer analyzed these readings.
The researchers found that the tiny vibrations in the lamp in response to sound (measured as tiny movements of a few hundred microns) were recorded as a measurable change in the light the sensor collected from the telescope. After processing the signal with software and filtering out the noise, they managed to recreate the audio recordings inside the room with remarkable accuracy: for example, researchers recreated an audible section of former US President Donald Trump’s speech and showed that this section was clear enough to be converted to text by Google’s Cloud Speech API. They also made a recording of The Beatles ‘ “let It be” so clear that the song-finding app Shazam instantly recognized it.
But this method has some limits. In their tests, the researchers used a lamp hanging from the ceiling. It is unclear whether the lamp placed in a fixed fixture or a ceiling fixture can vibrate enough to generate an audio signal of the same type. The sound and music recordings that the researchers used in the introduction were also higher than the average sound that people made when they chatted. In addition, the speakers have been brought to the highest volume level. But the researchers used a relatively inexpensive electro-optical sensor and an analog-to-digital converter.; he notes that they can use more expensive devices to capture lower sounds. In addition, LED lamps offer a signal-to-noise ratio of about 6.3 times that of an incandescent lamp and 70 times that of a fluorescent lamp.
According to Dan Boneh, a computer scientist and password expert at Stanford University, the researchers ‘ method represents an important and possibly practical form of what he calls a “side channel” attack, despite these negatives. In a side-channel attack, secrets are stolen with the help of unintentionally leaked information. ” This method is a nice application of side channels, ” says Boneh. “Although the stalactite requires a light bulb and high decibels, it is still very interesting. And this is the first time that such a thing has been shown to be possible. Attacks develop further, and future research will further develop this method over time.”
The research team, mentored by Yuval Elovici and Adi Shamir, co-inventors of the RSA encryption system used in many places, working at BGU, is not the first team to show that voice-related cases can be spied on. Researchers have known for years that sounds inside can be detected by bouncing laser light from a target’s window. Another research group showed in 2014 that with the help of a gyroscope on a smartphone that was attacked, sounds could be detected even if malware could not reach the phone microphone. Before that, the closest method to a lamp was what MIT, Microsoft and Adobe researchers called a “visual microphone” in 2014: the researchers found that an object that collects vibrations in the room (for example, an object that collects vibrations). by analyzing the video recorded with the help of a telescope (a packet of potato chips and a house plant), they were able to recreate the sounds and music.
But although this video-based method is versatile (because a light bulb in the room does not need to be seen), Nassi says that the video must be analyzed with software after recording in order to convert the light vibrations observed in an object into sounds that the object collects. The lamp, by contrast, makes real-time espionage possible. Since the vibrating object itself is a light source, the electro-optical sensor can capture vibrations with much simpler visual data.
According to Nassi, this could make the lamp significantly more practical compared to previous methods of espionage. “When you actually use it in real time, you can respond in real time instead of losing the opportunity,” he says.
Still, Nassi says the researchers published their findings not to enable spies or law enforcement, but to show people on both sides of the surveillance what is possible. ” We want to raise awareness of this type of attack vector, ” he says. “We’re not in the car supply game.”
The less likely it is to be targeted with this method, the easier it is to prevent it. Just cover the lamps hanging from the ceiling, or better yet, pull the curtains. Also, if you are paranoid enough to be concerned about such espionage games, we hope that you have used anti-vibration devices in the windows to prevent espionage with a laser microphone. You also cleaned your house of insects. And you removed the microphones from your phone and computer. After all, in this era when even a lamp has an ear, the work of a paranoid never ends.