SCADA: What Happens Next?

About this interactive

A SCADA system centralizes control of equipment spread across a plant, a pipeline or a city. It works in two directions at once. Data acquisition comes up: sensors measure pressure, flow, temperature or level, the RTUs and PLCs on the floor collect those readings, and the network carries them to the SCADA server, where operators see the whole system in one place. Supervisory control goes down: the server, or an operator at it, decides, and the command travels back to an RTU or PLC, which drives the pump, valve or motor. Two things follow. The server knows only what data acquisition tells it, so a wrong or altered reading leads to a wrong decision. And a controller carries out any command that reaches it, so whoever can send one, or change a setpoint in the SCADA software, can move real equipment. When a link or the server goes down, the RTUs and PLCs keep running their own programs, and what is lost is the view and the control from the center. To predict what happens, find which direction the event travels, and which part acts: a sensor measures, a controller acts, and the server decides from what it receives.

What you'll learn

Predict what a SCADA system does next when a reading comes in, a command goes out, or a part of the system fails
Trace a case through SCADA's two directions: data acquisition from sensors through RTUs or PLCs to the SCADA server, and supervisory control from the server back down to the equipment
Explain why SCADA acts only on the data it receives and why its controllers carry out any command that reaches them

Aligned to

CompTIA Security+

3.1 Compare and contrast security implications of different architecture models.

Key terms

Supervisory Control and Data Acquisition: An architecture in which a central server and its software gather readings from sensors and field units across a plant, pipeline or region and send commands back to them, used in critical infrastructure, where a security failure can damage physical equipment.
Supervisory Control: The function of a SCADA system that sends commands and instructions to field devices and equipment to direct their operations.
Data Acquisition: The function of a SCADA system that collects sensor and device data from the field to inform control decisions.
Remote Terminal Unit: A field device, often at an unstaffed site far from any building, such as a pipeline station or substation, that collects sensor readings and carries out commands for a SCADA system over a long-distance link and can keep running its equipment on its own; compromising one can give an attacker control of physical infrastructure.
Programmable Logic Controller: A rugged industrial computer that runs stored instructions to automate machinery and processes on a plant floor, reading its sensors and switching equipment in response; exploiting one can cause physical damage.
Sensor: In an industrial control system, a field device that measures one physical condition, such as pressure, temperature, flow or a tank's level, and reports it as a reading to an RTU or PLC, which passes it on to the SCADA system.
Protocol: A set of rules governing the format and transmission of data between devices.

Topics

Supervisory Control And Data Acquisition Supervisory Control Data Acquisition Remote Terminal Unit Programmable Logic Controller Interactive Predict

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