Charging Me and I Know Your Secrets!: Towards Juice Filming Attacks on Smartphones

Smartphones such as Android phones and iPhones are widely adopted worldwide and the number of smartphone users has increased dramatically. With the popularity of smartphones, the privacy of smartphone users are challenged by various malware and attacks. A large amount of malware has been developed and spread such as Soundcomber, Screenmilker, TouchLogger, and so on. In addition, some smartphone attacks are based on physical access to the phone like smudge attacks. All these have reminded current users to pay more attention for smartphone security such as installing anti-malware software to defend against malicious apps, which may reduce the effectiveness of most malware. In this paper, we identify a vulnerability of smartphone charging and design a new type of charging attacks (called juice filming attacks ) based on a standard USB connector and HDMI, which can steal users' secrets through automatically video-capturing their inputs (e.g., unlock patterns, PIN code). The efficiency of our designed attacks relies on the observations that users are not aware of any risk when charging their phones in public places and that most users would interact with their phone during the charging. Different from other malware and attacks, our designed juice filming attacks possess six major features: 1) be simple but quite efficient; 2) user unawareness; 3) does not need to install any apps on phone's side; 4) does not need to ask for any permissions; 5) cannot be detected by any current anti-malware software; 6) can be scalable and effective in both Android OS and iOS. To implement this attack, we employ a VGA/RGB frame grabber and further conduct several user studies to explore the feasibility and effectiveness of our attacks. Based on the understanding, we later propose several mitigation strategies to defend against such attacks.