How frequently must a Cyber Security Incident response plan be tested?

The correct answer is that a Cyber Security Incident response plan must be tested at least once every 36 calendar months according to NERC Critical Infrastructure Protection (CIP) standards. This requirement is established to ensure that organizations maintain an effective response to cyber security incidents and can promptly address potential threats or attacks. Regular testing helps in identifying weaknesses in the plan and provides an opportunity for personnel to familiarize themselves with their roles in the event of a cyber incident.

Testing the plan every 36 months strikes a balance between ensuring preparedness and manageable resource allocation for organizations. It allows for updates that reflect changes in technology, personnel, or threat landscapes without requiring excessive frequency that could detract from other important security activities.

Other frequencies mentioned do not align with this standard. While annual testing might seem reasonable, it is not stipulated by the requirements. Similarly, testing every six months would exceed the minimal expectations set forth by the requirements, imposing unnecessary burdens. Testing only when an incident occurs is not proactive and could leave the organization unprepared, as real-time responses may not be effectively practiced prior to an incident.