What is a 'security requirement' in the context of risk assessments?

In the context of risk assessments, a 'security requirement' refers to a specific condition that must be met to ensure the security of an industrial automation and control system (IACS). Security requirements are explicitly defined criteria or specifications that outline what must be achieved to protect the system from various threats, vulnerabilities, and risks.

These requirements are essential for establishing a security baseline that guides the design, implementation, and maintenance of security measures within the IACS. They are actionable and measurable, serving as a roadmap for organizations to strengthen their cybersecurity posture. By clearly outlining security requirements, organizations can focus their efforts on fulfilling these conditions, which helps in mitigating potential risks and enhancing overall system integrity.

The other options, while they might reflect different aspects of cybersecurity practices, do not accurately define what constitutes a security requirement in this context. For example, optional guidelines or recommendations do not impose strict conditions that must be adhered to, thereby lacking the enforceability and clarity of actual security requirements.