Inside Job: Understanding and Mitigating the Threat of External Device Mis-Binding on Android

In this paper, we present the first study on this new security issue, which we call external Device Mis-Bonding or DMB, under the context of Bluetooth-enabled Android devices. Our research shows that this problem is both realistic and serious: oftentimes an unauthorized app can download sensitive user data from an Android device and also help the adversary to deploy a spoofed device that injects fake data into the original device’s official app on the phone. Specifically, we performed an in-depth analysis on four popular health/medical devices that collect sensitive user information and successfully built end-toend attacks that stealthily gathered sensitive user data and fed arbitrary information into the user’s health/medical account, using nothing but Bluetooth permissions and public information disclosed by the phone. Our further study of 68 relevant deviceusing apps from Google Play confirms that the vast majority of the devices on the market are vulnerable to this new threat. To defend against it, we developed the first OS-level protection, called Dabinder. Our approach automatically generates secure bonding policies between a device and its official app, and enforces them when an app attempts to establish Bluetooth connections with a device and unpair the phone from the device (for resetting the Bluetooth link key). Our evaluation shows that this new technique effectively thwarts the DMB attacks and incurs only a negligible impact on the phone’s normal operations.