Repack Me If You Can

Abstract

A growing trend in repackaging attacks exploits the Android virtualization technique, in which malicious code can run together with the victim app in a virtual container. In such a scenario, the attacker can directly build a malicious container capable of hosting the victim app instead of tampering with it, thus neglecting any anti-repackaging protection developed so far. Also, existing anti-virtualization techniques are ineffective since the malicious container can intercept - and tamper with - such controls at runtime. So far, only two solutions have been specifically designed to address virtualization-based repackaging attacks. However, their effectiveness is limited since they both rely on static taint analysis, thus not being able to evaluate code dynamically loaded at runtime. To mitigate such a problem, in this paper we introduce MARVEL, the first methodology that allows preventing both traditional and virtualization-based repackaging attacks. MARVEL strongly relies on the virtualization technique to build a secure virtual environment where protected apps can run and be checked at runtime. To assess the viability and reliability of MARVEL, we implemented it in a tool, i.e., MARVELoid, that we tested by protecting 4000 apps with 24 different configurations of the protection parameters (i.e., 96k protection combinations). MARVELoid was able to inject the protection into 97.3% of the cases, with a processing time of 98 seconds per app on average. Moreover, we evaluated the runtime overhead on 45 apps, showing that the introduced protection has a negligible impact in terms of average CPU (<5%) and memory overhead (<0.5%).