Biblio

iOS is one of the most secure operating systems based on policies created and enforced by Apple. Though not impervious or free from vulnerabilities, iOS has remained resilient to many attacks partially based on lower market share of devices, but primarily because of tight controls placed on iOS development and application deployment. Locked iOS devices pose a specific hard problem for both law enforcement and corporate IT dealing with malicious insiders or intrusion scenarios. The need to recover forensic data from locked iOS devices has been of public interest for some time. In this paper, we describe a case study analysis of the iPhone 5c model and our attempts to use electromagnetic (EM) fault-injection as a side channel means to unlock the device. Based on our study, we report on our unsuccessful attempts in unlocking a locked iPhone 5c using this side channel-based approach. As a contribution, we provide initial analysis of the iPhone 5c processor's spectral mapping under different states, a brief survey of published techniques related to iPhone unlock scenarios, and a set of lessons learned and recommended best practices for other researchers who are interested in future EM-based iOS studies.

Modern operating systems, such as iOS, use multiple access control policies to define an overall protection system. However, the complexity of these policies and their interactions can hide policy flaws that compromise the security of the protection system. We propose iOracle, a framework that logically models the iOS protection system such that queries can be made to automatically detect policy flaws. iOracle models policies and runtime context extracted from iOS firmware images, developer resources, and jailbroken devices, and iOracle significantly reduces the complexity of queries by modeling policy semantics. We evaluate iOracle by using it to successfully triage executables likely to have policy flaws and comparing our results to the executables exploited in four recent jailbreaks. When applied to iOS 10, iOracle identifies previously unknown policy flaws that allow attackers to modify or bypass access control policies. For compromised system processes, consequences of these policy flaws include sandbox escapes (with respect to read/write file access) and changing the ownership of arbitrary files. By automating the evaluation of iOS access control policies, iOracle provides a practical approach to hardening iOS security by identifying policy flaws before they are exploited.

Recent literature on iOS security has focused on the malicious potential of third-party applications, demonstrating how developers can bypass application vetting and code-level protections. In addition to these protections, iOS uses a generic sandbox profile called "container" to confine malicious or exploited third-party applications. In this paper, we present the first systematic analysis of the iOS container sandbox profile. We propose the SandScout framework to extract, decompile, formally model, and analyze iOS sandbox profiles as logic-based programs. We use our Prolog-based queries to evaluate file-based security properties of the container sandbox profile for iOS 9.0.2 and discover seven classes of exploitable vulnerabilities. These attacks affect non-jailbroken devices running later versions of iOS. We are working with Apple to resolve these attacks, and we expect that SandScout will play a significant role in the development of sandbox profiles for future versions of iOS.