Pattern-Based Modeling of Cyber-Physical Systems For Analyzing Security

Cyber-physical systems are a crucial part of many infrastructure or production systems, and are spreading into other domains as part of the IoT (Internet-of-Things) wave. As cyber-physical systems act on the physical world, attacks could have severe consequences. At the same time, cyber-physical systems can be attacked like other IT systems. So it is essential that developers consider security during the design phase of software, to design adequate security protection for the system. This fact requires a structured security analysis right from the beginning. The initial input of such a security analysis is a system overview, e.g. in form of an architecture. It is a challenging task to provide the appropriate abstraction level of the system that allows identifying security threats and weaknesses. In the present paper, we describe a pattern that assists software developers in creating an architecture which captures the relevant elements for a security analysis. The interfaces of components may not only be accessible for authorized entities, but also for attackers. Therefore, we specify different interface types which enables one to identify relevant attacks for a specific interface type. We first present the solution part of our pattern as a meta-model, for which we then provide guidelines for its instantiation. As an example, we instantiate the pattern for a typical automation and control system. Last, we evaluate the suitability of our pattern by discussing how typical threats could be mapped to the different interface types.