NaClDroid: Native Code Isolation for Android Applications

Android apps frequently incorporate third-party libraries that contain native code; this not only facilitates rapid application development and distribution, but also provides new ways to generate revenue. As a matter of fact, one in two apps in Google Play are linked with a library providing ad network services. However, linking applications with third-party code can have severe security implications: malicious libraries written in native code can exfiltrate sensitive information from a running app, or completely modify the execution runtime, since all native code is mapped inside the same address space with the execution environment, namely the Dalvik/ART VM. We propose NaClDroid, a framework that addresses these problems, while still allowing apps to include third-party code. NaClDroid prevents malicious native-code libraries from hijacking Android applications using Software Fault Isolation. More specifically, we place all native code in a Native Client sandbox that prevents unconstrained reads, or writes, inside the process address space. NaClDroid has little overhead; for native code running inside the NaCl sandbox the slowdown is less than 10% on average.