Going through the motions: AR/VR keylogging from user head motions

Augmented Reality/Virtual Reality (AR/VR) are the next step in the evolution of ubiquitous computing after personal computers to mobile devices. Applications of AR/VR continue to grow, including education and virtual workspaces, increasing opportunities for users to enter private text, such as passwords or sensitive corporate information. In this work, we show that there is a serious security risk of typed text in the foreground being inferred by a background application, without requiring any special permissions. The key insight is that a user's head moves in subtle ways as she types on a virtual keyboard, and these motion signals are sufficient for inferring the text that a user types. We develop a system, TyPose, that extracts these signals and automatically infers words or characters that a victim is typing. Once the sensor signals are collected, TyPose uses machine learning to segment the motion signals in time to determine word/character boundaries, and also perform inference on the words/characters themselves. Our experimental evaluation on commercial AR/VR headsets demonstrate the feasibility of this attack, both in situations where multiple users' data is used for training (82% top-5 word classification accuracy) or when the attack is personalized to a particular victim (92% top-5 word classification accuracy). We also show that first-line defenses of reducing the sampling rate or precision of head tracking data are ineffective, suggesting that more sophisticated mitigations are needed.