THE MATHEMATICAL APPARATUS OF THE METHOD OF AS-SESSING THE RISK FROM CYBER ATTACKS CALCYBER

The purpose of the study is to create a scientifically based and affordable technology for automating the management of risks from cyber threats for ICS. Research method(s): mathematical modeling. Result(s) of the study: the paper describes and provides a method for calculating the risk from cyber threats for ICS of a new formalized method for assessing the risk from cyber-attacks CALCYBER, which is being developed at ICS RAS in order to create a scientifically based and affordable technology for automating activities to manage risks from cyber threats for automated process control systems (APCS). The method defines the concept of «production function» to denote protected assets of the object of control and the «hidden function» for designating malicious inclusions in the ICS. The concepts of damage in the form of a function with values in an ordinal scale, requirements for the availability and integrity of software elements as Boolean functions are introduced. Based on the availability property, the criterion for the regular operation of the automated process control system is determined, and the formulas for calculating risks are given. The conditions for searching for critical vulnerabilities and the stability of ICS cyber defense barriers are formulated. The reflection of the requirements of GOST R ISO/IEC 27005 in the developed CALCYBER method is analyzed. The article provides an example of the application of the developed method for vulnerability analysis, containing information about the CALCYBER project and existing software prototypes available for download and research. Scientific novelty: for the first time, the concept of production and hidden functions is formalized, for which the method of risk assessment for ICS is formulated.