The Extended Risk Assessment Form for IT/OT Convergence in IACS Security

Recently, security incidents that caused the shutdown or obstruction of the industrial automation and control systems (IACS) which support social infrastructure have increased rapidly. Many governments and businesses are addressing this urgent issue. IACS consists of two technologies, one is an information equipment based on information technology (IT) such as the Internet and cloud servers, and a control equipment based on operation technology (OT) such as controllers and sensing devices. The assets to be protected in IACS are not only IT information assets, as well as the functions and performance of OT related to human health and social services. For this reason, it has been known that the counter measures based on IT security alone are insufficient and incomplete. As an approach to this problem, IT/OT convergence has attracted attention in the IACS security problem. In order to bridge gaps of technical, human, and system gaps between IT and OT, new methodologies from the view of IT/OT convergence are being studied. This paper would discuss a security risk assessment for analyzing, designing counter measures and evaluating IACS security issues from the perspective of IT/OT convergence. Since the scope of assessment and the items to be examined will expand, we propose the extended risk assessment form that can take them into consideration. By using this form, it is possible to carry out security risk assessment covering IT and OT, safety and security, cyber and physical, as a series of sequences.