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ECUPrint—Physical Fingerprinting Electronic Control Units on CAN Buses Inside Cars and SAE J1939 Compliant Vehicles

We fingerprint 54 ECUs from 10 cars, one of them being a heavy-duty vehicle that is compliant to the SAE J1939 standard. These later specifications implemented in commercial vehicles offer concrete sender addresses in every CAN frame, making physical characteristics easier to link to specific ECUs. This is not the case for traffic collected inside passenger cars where the allocation of CAN bus identifiers is non-uniform, without explicit sender and receiver addresses, making ECU identification more challenging. While previous research has shown good separation between ECUs even when single features are used, e.g., skews or maximum voltage level, prior results are based on a small number of cars, while our larger experimental basis proves that single features are likely insufficient to separate between a large number of ECUs. Concretely, for a crisp separation, at least four features seem to be needed, i.e., mean voltage, max voltage, bit time and plateau time, while clock skews or any single voltage feature lead to overlaps. We provide clear experimental bounds on the intra and inter-distances regarding skews and voltage features, not neglecting environmental variations which may occur when the car is running.