Staying Secure and Unprepared: Understanding and Mitigating the Security Risks of Apple ZeroConf

With the popularity of today's usability-oriented designs, dubbed Zero Configuration or ZeroConf, unclear are the security implications of these automatic service discovery, "plug-and-play" techniques. In this paper, we report the first systematic study on this issue, focusing on the security features of the systems related to Apple, the major proponent of ZeroConf techniques. Our research brings to light a disturbing lack of security consideration in these systems' designs: major ZeroConf frameworks on the Apple platforms, including the Core Bluetooth Framework, Multipeer Connectivity and Bonjour, are mostly unprotected and popular apps and system services, such as Tencent QQ, Apple Handoff, printer discovery and AirDrop, turn out to be completely vulnerable to an impersonation or Man-in-the-Middle (MitM) attack, even though attempts have been made to protect them against such threats. The consequences are serious, allowing a malicious device to steal the user's SMS messages, email notifications, documents to be printed out or transferred to another device. Most importantly, our study highlights the fundamental security challenges underlying ZeroConf techniques: in the absence of any pre-configured secret across different devices, authentication has to rely on Apple-issued public-key certificate, which however cannot be properly verified due to the difficulty in finding a unique, nonsensitive and widely known identity of a human user to bind her to her certificate. To address this issue, we developed a suite of new techniques, including a conflict detection approach and a biometric technique that enables the user to speak out her certificate through 6 distinct, rare but pronounceable words to let those who know her voice verify her certificate. We performed a security analysis on the new protection and evaluated its usability and effectiveness using two user studies involving 60 participants. Our research shows that the new protection fits well with the existing ZeroConf systems such as AirDrop. It is well received by users and also providing effective defense even against recently proposed speech synthesis attacks.