AppShell: Making data protection practical for lost or stolen Android devices

Mobile apps continue to consume increasing amounts of sensitive data, such as banking credentials and classified documents. At the same time, the number of smartphone thefts is increasing at a rapid speed. As a result, there is an imperative need to protect sensitive data on lost or stolen mobile devices. In this work, we develop a practical solution to protect sensitive data on mobile devices. Our solution enables adaptive protection by pro-actively stepping up or stepping down data security based on perceived contextual risk of the device. We realize our solution for the Android platform in the form of a system called AppShell. AppShell does not require root privilege, nor need any modification to the underlying framework, and hence is a ready-to-deploy solution. It supports both in-memory and on-disk data protection by transparently encrypting the data, and discarding the encryption key, when required, for enhanced protection. We implement a working prototype of AppShell and evaluate it against several popular Android apps. Our results show that AppShell can successfully protect sensitive data in the lost devices with a reasonable performance overhead.