This paper presents an approach, using the process-algebra CSP, that aims to support systematic security testing of ECU components. An example use case regarding Over-The-Air software updates demonstrates the potential of our approach. Initial results confirm application code implemented in a typical automotive development environment can be translated into machine-readable format for the FDR refinement checker to formally verify security functions and identify any existing security flaws. Although still early stage work, the potential contribution towards automatically model-checking ECU components and, by composing several CSP models, larger systems is encouraging.