Decomposable Trust for Android Applications

Current operating system designs require applications (apps) to implicitly place trust in a large amount of code. Taking Android as an example, apps must trust both the kernel as well as privileged userspace services that consist of hundreds of thousands of lines of code. Malware apps, on the other hand, aim to exploit any vulnerabilities in the above large trusted base to escalate their privileges. Once malware escalates its privileges, additional attacks become feasible, such as stealing credentials by scanning memory pages or intercepting user interactions of sensitive apps, e.g., those used for banking or health management. This paper introduces a novel mechanism, called Anception, that strategically deprivileges a significant portion of the kernel and system services, moving them to an untrusted container, thereby significantly reducing the attack surface for privilege escalation available to malware. Anception supports unmodified apps, running on a modified Android kernel. It achieves performance close to native Android on several popular macro benchmarks and provides security against many types of known Android root exploits.