Resource Protection in Industrial Automation Systems Based on a Hybrid Zero Trust Architecture

Abstract

This study addresses the cybersecurity challenges of Industrial Automation and Control Systems (IACS) amid the accelerating convergence of Information Technology (IT) and Operational Technology (OT). A comparative analysis of the traditional zoning model, formalized in ISA/IEC 62443, and Zero Trust Architecture (ZTA) establishes the necessity of transitioning from perimeter-based defenses to resource-oriented security paradigms. To this end, a hybrid architectural framework is proposed, wherein IEC 62443 provides the foundational zoning methodology while ZTA serves as a dynamic enforcement mechanism for granular, context-aware access control. Furthermore, a four-stage hybrid migration model is developed to enable phased ZTA integration in heterogeneous OT environments, explicitly addressing legacy infrastructure constraints, deterministic real-time requirements, and industrial protocol specifics. Experimental validation demonstrates that the proposed framework significantly mitigates lateral movement risks and blocks unauthorized access attempts, thereby enhancing cyber resilience while preserving operational continuity and compliance with established industry standards.