Until very recently it was widely believed that iOS malware is effectively blocked by Apple's vetting process and application sandboxing. However, the newly presented severe malicious app attacks (e.g., Jekyll) succeeded to undermine these protection measures and steal private data, post Twitter messages, send SMS, and make phone calls. Currently, no effective defenses against these attacks are known for iOS.

The main goal of this paper is to systematically analyze the recent attacks against iOS sandboxing and provide a practical security framework for iOS app hardening which is fully independent of the Apple's vetting process and particularly benefits enterprises to protect employees' iOS devices. The contribution of this paper is twofold: First, we show a new and generalized attack that significantly reduces the complexity of the recent attacks against iOS sandboxing. Second, we present the design and implementation of a novel and efficient iOS app hardening service, XiOS, that enables fine-grained application sandboxing, and mitigates the existing as well as our new attacks. In contrast to previous work in this domain (on iOS security), our approach does not require to jailbreak the device. We demonstrate the efficiency and effectiveness of XiOS by conducting several benchmarks as well as fine-grained policy enforcement on real-world iOS applications.