JFCGuard: Detecting juice filming charging attack via processor usage analysis on smartphones

Smartphones have become necessities in people's lives, so that many more public charging stations are under deployment worldwide to meet the increasing demand of phone charging (i.e., in airports, subways, shops, etc.). However, this situation may expose a hole for cyber-criminals to launch various attacks especially charging attacks and threaten users' privacy. As an example, juice filming charging (JFC) attack is able to steal users' sensitive and private information from both Android OS and iOS devices, through automatically recording phone screen and monitoring users' inputs during the whole charging period. More importantly, this attack does not need any permission or installing any pieces of apps on users' side. The rationale is that users' information can be leaked through a standard micro USB connector that employs the Mobile High-Definition Link (MHL) standard. Motivated by the potential damage of JFC attack, in this work, we investigate the impact of JFC attack on processor usage including both CPU and GPU usage. It is found that JFC attack would cause a noticeable usage increase when connecting the phone to the JFC charger. Then, we design a security mechanism, called JFCGuard, to detect JFC attack based on processor usage analysis for smartphone users. In the evaluation, we perform a user study with over 250 participants and the results demonstrate that JFCGuard can identify JFC attack in an effective way. Our work aims to complement existing research results and stimulate more research in this area.