Vulnerability of MEMS Gyroscopes to Targeted Acoustic Attacks

The goal of this paper is to assess the vulnerability of MEMS-based gyroscopes to targeted ultrasonic attacks. Towards this objective, a surface micromachined planar MEMS gyroscope is fixed in space and subjected to ultrasonic waves with frequencies near its driving frequency. The ultrasonic input is shown to produce deceptive low-frequency angular velocity readings in the yaw direction. Using physics-based mathematical model of the gyroscope, it is shown that the misalignment between the sensing and driving axes of the gyroscope is the main culprit behind the vulnerability of the gyroscope to ultrasonic attacks. It is also concluded that ultrasonic attacks on MEMS gyroscopes can impose high-security risks. In addition to the attack being barely audible, the resulting deceptive angular velocity signals have a very low frequency content which cannot be attenuated by adding a low-pass filter. Furthermore, the current approach implemented to eliminate unwanted vibrations from the output signal of the MEMS gyroscopes by using an identical proof mass to perform differential measurements is clearly ineffective in shielding the gyroscope from ultrasonic attacks. As such, new measures have to be taken to protect MEMS gyroscopes from targeted acoustic attacks.