Luigi Sciolla

Alessio Merlo, Antonio Ruggia, Luigi Sciolla et al.

App repackaging refers to the practice of customizing an existing mobile app and redistributing it in the wild to fool the final user into installing the repackaged app instead of the original one. In this way, an attacker can embed malicious payload into a legitimate app for different aims, such as access to premium features, redirect revenue, or access to user's private data. In the Android ecosystem, apps are available on public stores, and the only requirement for an app to execute properly is to be digitally signed. Due to this, the repackaging threat is widely spread. Anti-repackaging techniques aim to make harder the repackaging process for an attack adding logical controls - called detection node - in the app at compile-time. Such controls check the app integrity at runtime to detect tampering. If tampering is recognized, the detection nodes lead the repackaged app to fail (e.g., throwing an exception). From an attacker's standpoint, she must detect and bypass all controls to repackage safely. In this work, we propose a novel anti-repackaging scheme - called ARMAND - which aims to overcome the limitations of the current protection schemes. We have implemented this scheme into a prototype - named ARMANDroid - which leverages multiple protection patterns and relies on native code. The evaluation phase of ARMANDroid on 30.000 real-world Android apps showed that the scheme is robust against the common attack vectors and efficient in terms of time and space overhead.

Alessio Merlo, Antonio Ruggia, Luigi Sciolla et al.

App repackaging refers to the practice of customizing an existing mobile app and redistributing it in the wild. In this way, the attacker aims to force some mobile users to install the repackaged(likely malicious) app instead of the original one. This phenomenon strongly affects Android, where apps are available on public stores, and the only requirement for an app to execute properly is to be digitally signed. Anti-repackaging techniques try counteracting this attack by adding logical controls in the app at compile-time. Such controls activate in case of repackaging and lead the repackaged app to fail at runtime. On the other side, the attacker must detect and bypass the controls to repackage safely. The high-availability of working repackaged apps in the Android ecosystem suggests that the attacker's side is winning. In this respect, this paper aims to bring out the main issues of the current anti-repackaging approaches. The contribution of the paper is three-fold: 1) analyze the weaknesses of the current state-of-the-art anti-repackaging schemes (i.e., Self-Protection through Dex Encryption, AppIS, SSN, SDC, BombDroid, and NRP), 2) summarize the main attack vectors to anti-repackaging techniques composing those schemes, and 3) show how such attack vectors allow circumventing the current proposals. The paper will also show a full-fledged attack to NRP, the only publicly-available anti repackaging tool to date.