Method for calculating the cyber resilience of levels 2-1 of the Purdue model against specialized technological trojan software

Ensuring the cyber resilience of a critical information infrastructure facility, particularly its technological system, is among the primary the primary responsibilities of the management of modern public and private enterprises, both in Ukraine and globally.Cyberattacks targeting the technological systems of critical infrastructure facilities are typically conducted by hacker groups (cyber threat actors) sponsored by state entities. The objectives of such cyberattacks may include both cyber espionage and destructive cyber impacts on an enterprise’s physical production systems, potentially leading to substantial financial losses, disruption of technological process and even man-made disasters. The principal tool employed by cyber threat actors to execute such cyberattacks is specialized technological Trojan software.The information system of a critical infrastructure facility are divided into communication and technological systems (also called corporate and industrial, respectively), each of which is an object of critical information infrastructure. The most dangerous is a cyberattack at level 2-1 (according to the Purdue model) of the technological system of a critical infrastructure facility. This is due to the fact that the most important information subsystems of the technological system of a critical infrastructure facility are deployed and operate at levels 2-1 of the model - Basic Process Control Systems and Safety Instrumented Systems. The cyber resilience of the Safety Instrumented Systems constitutes a critical component of the overall cyber resilience of the technological system of a critical infrastructure facility.