Security risk assessment-based cloud migration methodology for smart grid OT services

Abstract

The primary goal of this paper is to present a security risk assessment-based methodology for migrating sensitive Smart grid operational technology (OT) services to the computing cloud, either on or off-premise. We created a baseline system architecture diagram for smart grid Industrial Control Systems (ICS) aligned with the IEC-62443 model of security zones. We identified potential threat sources and threats which might affect the confidentiality, integrity, and availability (CIA triad) of OT services. We defined a threat impact and likelihood assessment strategy tailored for use in smart grids. Based on the combined impact and likelihood of threats we present a risk matrix, a tabular risk assessment template, and a baseline cloud migration strategy. We test our methodology on two cloud migration case studies, namely a large distribution system operator (DSO) with a complex OT environment; and a small DSO with limited OT capabilities, budget, and IT staff. As there are no risk assessment-based studies which tackle the problem of migrating smart grid OT services to a cloud computing architecture in a systematic way, our method will be a valuable asset for any smart grid system owner/operator. Which will be able to guide them in choosing an optimal cloud migration strategy, both fitting their specific requirements and maintaining an adequate level of information security.