How often should risk assessments be conducted for IACS?

Conducting risk assessments periodically and whenever significant changes occur in the system or environment is aligned with best practices in cybersecurity, particularly within the context of the ISA/IEC 62443 standards.

This approach acknowledges that risks evolve over time due to a variety of factors, including alterations in the industrial automation and control systems (IACS), changes in operational processes, technological advancements, emerging threats, and the introduction of new regulatory requirements. A risk assessment conducted periodically ensures that the organization maintains an updated understanding of its risk landscape, allowing for timely identification and mitigation of vulnerabilities.

Additionally, assessing risks after significant changes is crucial as these modifications can introduce new vulnerabilities or alter existing risk profiles. Such changes may include updates to software, hardware, system architecture, or even changes in team dynamics or operating procedures. By closely monitoring changes and conducting assessments accordingly, organizations can better protect their IACS against potential threats and maintain compliance with industry standards.

In contrast, assessments conducted only during initial setup or on a fixed monthly schedule regardless of system changes might lead to either a false sense of security or unnecessary resource allocation. Thus, understanding the dynamic nature of risk is vital for effective management in IACS environments.