Designing of Functionally Stable Information Systems Optimal for a Minimum of Losses

When designing information systems it is necessary to ensure the optimality of expenditures to protect against information security incidents. The main causes of incidents are analyzed. The use of the term "functional stability", which combines both malicious and unintentional causes of incidents, is proposed. The concept is introduced and the proposed measure of criticality of information resources for the organization. The model of losses from incidents is constructed depending on expenditures on information security. The general dependence of optimal expenditures on information security was found depending on the level of criticality of information resources.