Comparing cybersecurity and functional safety risk assessments

As number of cyberattacks have increased, safety systems in machines can also be endangered. This means that in safety assessments also cybersecurity issues need to be considered from the safety viewpoint. This can be done in a single mutual analysis or in separate analyses by considering the domain specific risks. Risk assessment is the tool to identify and assess the threats and vulnerabilities of the safety related systems.
There are many new standards, requirements and proposals, which give guidelines for cybersecurity. New Machinery Regulation (EU) 2023/1230 of June 2023 gives some cybersecurity requirements, which were not in the current Machinery Directive (2006/42/EC). The new Machine Regulation makes a safety conscious connection between safety and cybersecurity. There are also many new cybersecurity requirements and standards, which machine manufacturers need to consider in the near future. These new requirements can cause a lot of work, but they can also show new business opportunities. All providers related to machinery systems need to show that their customers can rely on the cybersecurity measures and documentation that the subsystem or the service provider has delivered.
The primary objective of safety analyses is to avoid accidents and the primary objective of cybersecurity analyses is to prevent or minimize the effects of cyberattacks. The primary objectives are different and it affects the risks that need to be considered in the analysis.
The main objectives of functional safety attributes are to maintain integrity and, in many cases, also availability of the control system. The main objectives of cybersecurity attributes are to maintain integrity, availability and confidentiality. Impaired integrity means that the system is not operating as it should and for example a safety function can be lost. Impaired or reduced availability means that the access into the system is limited and the system does not operate as intended. This can be a safety issue or violation of cybersecurity objectives depending on the system and its operations. Confidentiality is not straight a safety issue, but it is cybersecurity matter. However, confidentiality issue can change the threats and vulnerabilities of the system, and therefore the system may need to be to be reevaluated.
It is practical to make the cybersecurity and safety analyses separately, but cooperation is needed, especially, in risk identification and risk mitigation phase. Risk identification is the most important phase of the risk assessment and therefore cooperation and resources are needed in this phase. In risk mitigation phase the safety and security measures need to be considered in order to have congruent measures and to avoid conflicts between objectives.