The functional model of stage access to a separate computer hardware in the process of a virus attack in computer systems

Background. Increasing the adequacy of mathematical models of the impact of malicious software (MS), used to substantiate the requirements for the characteristics and directions for improving the anti-virus mechanisms of computer systems (CS), can be achieved by using the methodological apparatus of functional modeling. The purpose of the studyis to substantiate a methodological apparatus for formalizing the threats of MS in order to construct adequate mathematical models for assessing the temporal characteristics of such threats. Materials and methods. The solution to the problem of constructing functional models in computer systems is based on the methodology of functional modeling, systems analysis and graph theory. Rusults. A procedure for constructing mathematical models of the temporal characteristics of threats of MS has been substantiated and implemented, including: a stage of detailing the objective function “Impact of MS”, a stage of establishing the order of execution of its functional components at each level of decomposition, a stage of forming the space of MS features, a stage of presenting the model in the form of graphs and a stage of forming analytical expressions for assessing the temporal characteristics of the threat. Conclusions. The adequacy of mathematical models of the temporal characteristics of threats of such impact, achieved through the functional decomposition of the objective function “Impact of MS”, allows for the validity of requirements for the directions of improvement of anti-virus mechanisms of the CS.