Amazon Echo Can Be Fooled by Silent Laser Commands

A team of specialists from the University of Electro-Communications in Tokyo (Japan) and the University of Michigan (USA) have developed a method that allows digital assistants to receive silent voice commands using a laser.

The discovery began when Takeshi Sugawara, a researcher at the University of Electro-Communications, noticed strange behavior from his iPad. He found that when a powerful laser was directed at the tablet’s microphone, it inexplicably interpreted the laser as sound. By modulating the laser’s intensity in a sinusoidal pattern at a frequency of 1,000 oscillations per second, Sugawara created a high-frequency sound wave that the iPad’s microphone detected and converted into an electrical signal.

After six months of research, Sugawara and a group of researchers from the University of Michigan turned this photoacoustic effect into something more significant. The scientists learned how to “talk” to any device capable of receiving voice commands using a laser, including smartphones, Amazon Echo smart speakers, Google Home, Facebook Portal devices with video calling, and more. The researchers were able to send light-based commands from hundreds of meters away, using them to open garages, make online purchases, and more.

Experiments revealed that if a laser is aimed at a microphone and its intensity is modulated at a precise frequency, the light somehow causes the microphone’s membrane to vibrate at the same frequency. Over time, the researchers adjusted the laser’s intensity to match the frequency of the human voice. As a result, the microphone converted the light waves into electrical signals just like it would with sound waves, effectively receiving silent voice commands. If an infrared laser is used, the attack on the device’s microphone becomes not only inaudible but also invisible.