Systematic analysis of cyber-attacks on CPS-evaluating applicability of DFD-based approach

Cyber-Physical Systems (CPSs) consist of as well as interact with cyber and physical elements. This creates multiple vectors for CPS-internal (i.e., within CPS) as well as for CPS-external (i.e., between CPS itself and its environment) Cyber-Physical Attacks. We argue that an effective Cyber-Physical Defense can only be elaborated if possible attacks on CPS can be identified and assessed in a systematic manner. In this paper, we focus on cyber-attacks only. Our contribution in this paper is the following. We assess the applicability of Data Flow Diagrams (DFD) for the systematic analysis of cyber-attacks against CPS. In this context, we introduce several extensions to DFD. We evaluate the analysis procedure by applying it on a comparatively simple example of a quad-rotor UAV. The selected UAV is fully functioning and contains multiple structural elements representative for more complex systems. At the same time, its simplicity enables an in-depth manual analysis. Our analysis shows that cyber-attacks executed against CPS can lead to various cyber-physical interactions. This, in turn, creates novel challenges for CPS defense. Finally, we outline the preliminary results of our work towards a Taxonomy of Cyber-Physical Attacks.