Fast or Secure? Push the Limit of Privacy Leakage Threat via Charging Side-Channel Attacks

Mobile devices have become ubiquitous, along with charging technology evolving rapidly. However, recent research has revealed a privacy vulnerability. Power traces in USB cables during charging can be maliciously exploited to eavesdrop on users' private information. Existing attacks typically measure either voltage or current to characterize power traces in low-power USB charging (5V 1A). In this paper, we present a novel charging side-channel attack that broadens the attack surface to include fast charging. Our approach works for both wired and wireless charging scenarios. It combines both voltage and current traces for a more comprehensive threat analysis. We systematically explore the risk of information leakage during different operations, including screen inputs (password and keystroke inference), screen outputs (application/display detection), acoustic outputs (loudspeaker eavesdropping), and acoustic inputs (microphone eavesdropping). In particular, such duplex acoustic eavesdropping via charging side channels has not been studied before. Extensive experiments demonstrate that our attacks pose real-world threats. As a countermeasure, we propose design suggestions for future fast charging systems to prevent privacy leaks.

• Security and privacy → Side-channel analysis and countermeasures; Mobile and wireless security.