RootAgency: A digital signature-based root privilege management agency for cloud terminal devices

Rooting an Android device can be a voluntary behavior from end users with various motivations, such as removing OEM pre-installed apps. This leads to an increase in opportunity of privilege escalation for malwares. The existing root privilege management schemes rely on the end users to make privilege granting decisions for all legal and illegal apps installed on the device. However, unskilled end users are incapable, or are careless in determining which privileges are appropriate for what type of app. To address this issue, a root privilege management agency named RootAgency is proposed, which adopts a digital signature scheme to guarantee the exclusive root-privilege-granting opportunities of authenticated apps. RootAgency authenticates an app by checking whether it holds the signature generated by the secret key, and grants the root privilege when a signed app submits the request. Moreover, it verifies the app's integrity to prevent it from repackaging. Thus, the users are not involved in decision making while confronting root requests. The proposed scheme ensures the security of rooted Android devices, and enhances the security of mobile terminal devices. This diminishes the threat to cloud infrastructure from root-misused Android devices. In addition, a prototype is implemented to evaluate its effectiveness, efficiency, and overhead. The experimental results show that RootAgency is widely compatible and its performance overhead is reasonable.