The most significant concern for an IS auditor when reviewing an industrial control system (ICS) that uses older unsupported technology in the scope of an upcoming audit is that there is a greater risk of system exploitation. System exploitation is an attack that occurs when an unauthorized entity or individual takes advantage of a vulnerability or weakness in a system to compromise its security or functionality. System exploitation can cause harm or damage to the system or its users, such as data loss, corruption, theft, manipulation, denial of service (DoS), etc. An ICS that uses older unsupported technology poses a high risk of system exploitation, as older technology may have known or unknown vulnerabilities or defects that have not been patched or fixed by the vendor or manufacturer, and unsupported technology may not receive any updates or support from the vendor or manufacturer in case of issues or incidents. Attack vectors are evolving for industrial control systems is a possible concern for an IS auditor when reviewing an ICS that uses older unsupported technology in the scope of an upcoming audit, but it is not the most significant one. Attack vectors are methods or pathways that attackers use to gain access to or attack a system. Attack vectors are evolving for industrial control systems, as attackers are developing new techniques or tools to target ICSs that are increasingly connected and complex. However, this concern may not be specific to older unsupported technology, as it may affect any ICS regardless of its technology level. Disaster recovery plans (DRPs) are not in place is a possible concern for an IS auditor when reviewing an ICS that uses older unsupported technology in the scope of an upcoming audit, but it is not the most significant one. DRPs are documents that outline the technical and operational steps for restoring the IT systems and infrastructure that support critical functions or processes in the event of a disruption or disaster. DRPs are not in place, as they may affect the availability and continuity of the ICS and its functions or processes in case of a failure or incident. However, this concern may not be related to older unsupported technology, as it may apply to any ICS regardless of its technology level. Technical specifications are not documented is a possible concern for an IS auditor when reviewing an ICS that uses older unsupported technology in the scope of an upcoming audit, but it is not the most significant one. Technical specifications are documents that describe the technical characteristics or requirements of a system or component, such as functionality, performance, design, etc. Technical specifications are not documented, as they may affect the understanding, maintenance, and improvement of the ICS and its components. However, this concern may not beassociated with older unsupported technology, as it may affect any ICS regardless of its technology level.