We can close doors with the today’s technology: it is enough that it is domotized and that the system is compatible with Google Home or Amazon Alexa, for example. The “Ok, Google. Open the garage” can be very useful, but it leaves a security hole that can be exploited with a laser.
It may seem like science fiction or something very complicated to do, but no: the laser light can be adapted to interact with the microphones of a smart speaker by making it think is picking up sound waves; so it’s possible to send commands at a distance of up to 50 meters. If we follow the example of the garage door, it would be possible to open it from outside the house just by pointing the laser at Google Home through the window.
While it’s a problem, because anyone could control a smart speaker and execute extremely delicate commands (always with the necessary tools), solving it is impossible because it’s part of how devices’ microphones work, whether they’re smart speakers or mobile speakers.
The “hacking” mechanism, developed by the University of Michigan and the University of Electro-Communications in Tokyo, demonstrates how it is possible to modulate the human voice through a standard 60 mW laser. The physics behind the discovery is not too complex: the laser heats the microphone of the diaphragm and expands the surrounding air, creating an identical pressure bubble to that formed by the sound passing through the diaphragm. In this way it is possible to transmit voice commands using light.
The discovery is part of a paper called “Lights commands”. It is impossible to patch as hacking makes use of the natural operation of microphones. The only solution is to keep intelligent loudspeakers away from visible areas of the house, especially those facing a window.