A PLC is a rugged industrial computer that reads sensors, runs control logic, and sends commands to physical equipment such as pumps, valves, motors, and chemical dosing systems. In water plants and other critical facilities, PLCs are part of operational technology (OT), so their actions can directly affect safety, service, and equipment wear.
PLCs matter in cyber security because compromising them can move an attack from the IT network into the process itself. Attackers may try to reach PLCs through exposed remote access, weak credentials, poor segmentation, or unsafe engineering tools. Defenders protect PLCs by limiting who can connect, isolating control networks, inventorying assets, and monitoring for unauthorized programming or configuration changes. Even brief access can let an intruder alter setpoints, stop processes, or disguise malicious changes, so PLC security is central to resilience in industrial environments.