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Abstract

Baseband processors are reachable over the radio at all times. Their most security-relevant logic runs deep inside protocol state machines: the control-plane handlers that gate registration, authentication, and session setup. Analyzing that logic systematically requires introspecting the firmware as it runs, which makes re-hosting the baseband necessary. Existing re-hosting work approximates the execution environment and under-approximates the SoC complexity of the baseband processor together with its surrounding components, bringing this state practically out of reach. We instead model each surrounding component, co-processors, SIM, application processor, from what a real device does, and step them in lockstep with the baseband on one shared clock. That makes faithfulness checkable at component interfaces, rather than assumed.