Evaluation of the Effectiveness of Cyber-Physical Protection Systems Considering the Degradation of Electronic Security Systems

This paper introduces a stochastic degradation model for Electronic Security Systems (ESS) within Cyber-Physical Protection Systems (CPPS). The model demonstrates how CPPS effectiveness is influenced by three major groups of factors: component aging processes, accumulation of adversary knowledge and skills, and technological advancements in attack tools, along with random vulnerability events and periodic maintenance actions. Each factor is represented by an appropriate distribution such as normal, logarithmic, or Bernoulli, providing a simplified yet representative set of degradation and recovery processes. System effectiveness SEi in month i is defined as max(100 − Xi, 0), where Xi aggregates the cumulative declines and improvements. Monte Carlo simulations (using hypothetical data and assumptions) reveal a characteristic degradation curve: high initial performance followed by accelerated decline, punctuated by minor recoveries due to maintenance. A case study indicates that the traditional EASI approach, which neglects degradation, substantially overestimates CPPS resilience over long time horizons. Consequently, we advocate incorporating the SEi metric into risk assessments and adopting adaptive maintenance schedules better aligned with real-world wear and evolving threats. Although based on hypothetical parameters, this model provides a foundation for calibration with operational data and for developing dynamic modernization and upkeep policies.