Phone light sensors can be misused
It has been proven that the ambient light sensor found in phones and tablets can be misused by hackers.
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Today, mobile phones are frequently used in daily life for a wide variety of tasks, such as making payments, advancing work processes, and even noting down the strange dreams we have at night. However, unfortunately, these technology products, which seem like lifesavers, can also be used to target us. A new study conducted by MIT researchers has shown how hackers can exploit a phone's light sensor to monitor and reconstruct our activity.
Ambient light sensors are used by phones to detect surrounding light levels and adjust screen brightness accordingly if the automatic adjustment setting is on. While other phone features like the camera or microphone require user permission for apps to access them, light sensors generally do not require such permission, and researchers believe this detail can be exploited.
AN ALGORITHM THAT CAN USE VARIATIONS CAPTURED BY THE LIGHT SENSOR
The MIT team, led by Yang Liu, developed an algorithm that can use variations captured by the light sensor to reconstruct images of a person's touch interactions, such as scrolling, with their phone.
In addition to testing the algorithm on an off-the-shelf Android tablet in several scenarios, including placing a puppet in front of the screen and using a mannequin, cardboard cutout, or human hand to touch it, they also tried to find out if it could detect and capture gestures while watching videos. The results revealed that light sensor data could be used to detect interactions with the screen and create images of them. In a statement, Liu said, “This imaging privacy threat had never been shown before.”
Fortunately, this method, which seems quite alarming, appears to be far from becoming a threat. The rate at which images were captured in the study was only one frame every 3.3 minutes; in other words, it was slow enough to make it almost impossible for someone trying to capture the images to track your phone interactions in real time. Even when they captured images from a natural video, the pictures could be quite blurry.
Nevertheless, the researchers suggest some ways that could help mitigate some potential risks. Since the main target is software, they suggest that access to ambient light sensors should be restricted, requiring users to grant permission just as they do for camera or microphone requests.
They also suggest placing a limit on the capabilities of the sensors, keeping the sensitivity and speed low enough to prevent high-resolution images, and placing the sensor on the side of the device where it cannot detect the most revealing movements.
The study was published in Science Advances.