An RTU, or Remote Terminal Unit, is an industrial controller used to collect telemetry, monitor field equipment, and send control commands at remote sites such as substations, pumps, pipelines, and treatment plants. It usually sits at the edge of an OT network and bridges sensors, actuators, and central SCADA systems.
RTUs matter because they often control real-world processes while remaining reachable over networks or legacy maintenance paths. If an attacker gains access to an RTU, they may be able to read operational data, change configuration, or manipulate equipment. Common attack paths include weak credentials, exposed management services, and outdated remote access features. Defenses focus on role-based access control, strong authentication, network segmentation, restricted firewall rules, and minimizing legacy interfaces. In practice, securing an RTU means treating it as both a control device and a high-value network target.