Bifröst: Apple's Rainbow Bridge for Satellite Communication (37c3)

Apple's cutting-edge emergency SOS and location sharing services provide crucial communication alternatives when no cellular network is available. This talk will shed light on how these satellite services work, how they are integrated into existing fall and crash detection, present the security measures employed to safeguard resource access and privacy, and explore how this communication is embedded within the operating system. With the release of the iPhone 14, users can reach out to emergency services by sending an SOS message via a satellite link directly from their phone. This use of the GlobalStar network facilitates two-way communication with emergency responders through the Messages app. Users can easily send text messages and respond to queries. This communication channel, due to its sensitive nature, demands robust security and authentication. It is imperative for Apple to ensure that the system is foolproof, negating the possibility of dispatching emergency responders to incorrect locations or individuals. Equally significant is the protection of the privacy of those in need, including their location and the nature of their emergency. In our talk, we demonstrate how a rooted iPhone without satellite capabilities can be tricked into thinking that it can communicate with the satellite network. This technique allows us to trigger various emergency situations without actually contacting emergency services. On the rooted iPhone, we can then inspect the transport security and key derivation while these features are being used. We will present various insights into the proprietary satellite communication protocol based on this analysis. Moreover, Apple's satellite features allow users to share their location in Find My with up to ten friends via a satellite link. This capability serves as a convenient tool for staying connected with friends and family while venturing off the beaten path. We’ll take a look into how this new Find My extension is implemented. about this event: https://events.ccc.de/congress/2023/hub/event/bifrost_apple_s_rainbow_bridge_for_satellite_communication/