mmEve: eavesdropping on smartphone's earpiece via COTS mmWave device

Earpiece mode of smartphones is often used for confidential communication. In this paper, we proposed a remote(>2m) and motion-resilient attack on smartphone earpiece. We developed an end-to-end eavesdropping system mmEve based on a commercial mmWave sensor to recover speech emitted from smartphone earpiece. The rationale of the attack is based on our observation that, soundwaves emitted from the smartphone's earpiece have a strong correlation with reflected mmWaves from the smartphone's rear. However, we find the recovered speech suffers from the sensor's self-noise and smartphone user's motion which limit attack distance to less than 2m, causing limited threats in real world. We modeled the motion interference under mmWave sensing and proposed a motion-resilient solution by optimizing the fitting function on I/Q plane. To achieve a practical attack with reasonable attack distance, we developed a GAN-based denoising scheme to eliminate the noise pattern of the sensor, which boosted the attack range to 6--8m. We evaluated mmEve with extensive experiments and find 23 different models of smartphones manufactured by Samsung, Huawei, etc. can be compromised by the proposed attack.