Chapter 10 — OT, IoT and cyber-physical security: orientation
Lesson map
Lesson 10 published. Map, example, EX028.
flowchart TD
N0["Learning outcomes"]
N1["10.1 Three overlapping terms"]
N2["10.2 The refrigeration loop"]
N3["10.3 Guidance map"]
N4["10.4 Safety stays separate"]
N5["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5
N5 --> EX["Worked example"]
EX --> Q["Exercise EX028"]
Logical drawing
flowchart LR
N0["Learning outcomes"]
N1["10.1 Three overlapping terms"]
N2["10.2 The refrigeration loop"]
N3["10.3 Guidance map"]
N4["10.4 Safety stays separate"]
N5["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> Q["EX028"]
[Learning outcomes]
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[10.1 Three overlapping terms]
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[10.2 The refrigeration loop]
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[10.3 Guidance map]
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v
[10.4 Safety stays separate]
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v
[Synthesis]
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v
[Worked example] --> [Exercise EX028]
Learning outcomes
You will (1) define OT, IoT and cyber-physical systems in NCS terms; (2) describe the refrigeration control loop; (3) name the main guidance documents and who they are for; and (4) explain why safety systems stay outside security changes.
10.1 Three overlapping terms
Operational technology monitors and controls physical processes — here, compressors, evaporator fans and valves. IoT devices are network-connected sensors and actuators — here, the wireless temperature loggers and cameras. A cyber-physical system is the loop of sensing, computing and acting on the physical world. NCS is all three at once.
At NCS the overlap is visible in one room: Freezer-2's probe feeds PLC-R1, while a wireless logger in the same room reports through GW-LOG to the cloud. One is OT, the other IoT, and both describe the same physical temperature, which is what makes the two-probe comparison in Chapter 24 possible.
10.2 The refrigeration loop
A temperature probe in Freezer-2 reports −21 °C; PLC-R1 compares it with the −22 °C setpoint and increases compressor capacity; more refrigerant evaporates, the room cools, and the probe reports again. An attacker who changes the setpoint, falsifies the probe or overrides the compressor command breaks the loop. ATT&CK for ICS T0836 Modify Parameter covers the setpoint case.
Priya's map of this loop, probe TT-F2 → PLC-R1 → compressor C-1 → evaporator → room → TT-F2, adds two independent paths: the wireless logger's second temperature view and the gas-detection panel that trips ventilation without PLC-R1.
10.3 Guidance map
NIST SP 800-82r3 guides OT security programmes for asset owners such as NCS. The IEC 62443 series covers industrial automation and control systems for owners, integrators and product suppliers. NIST IR 8259 describes cybersecurity activities for IoT device manufacturers, and ETSI EN 303 645 sets a baseline for consumer IoT products — useful as a checklist for buying loggers and cameras.
Priya uses EN 303 645 for exactly that purpose: her vendor questionnaire for the loggers asks the 5.1, 5.2, 5.3, 5.5 and 5.8 questions before NCS buys more.
The answers then decide whether a compensating control, such as comparing logger and PLC probes, is needed.
10.4 Safety stays separate
Ammonia gas detection and emergency ventilation are life-safety systems. Security work may observe and report on them, but changes go through the safety owner and the refrigeration engineer, never as a side effect of a firewall project.
At NCS this rule applies directly to Priya's firewall work. When she moved the dock cameras into their own zone, she confirmed with the refrigeration engineer that the gas-detection panel had no network connection the change could affect. If it had, the change would have gone to the safety owner first. Her reports may note that the gas-detection panel trips ventilation without PLC-R1, which reduces several cyber scenarios, but she does not test or reconfigure it.
Worked example (synthetic NCS)
Priya maps the Freezer-2 loop: probe TT-F2 → PLC-R1 → compressor C-1 → evaporator → room → TT-F2. Beside it she notes the independent paths: wireless loggers give a second temperature view to the cloud, and the gas-detection panel trips ventilation without PLC-R1. Both reduce the chance that one compromise hides a problem.
Synthetic case — Northgate Cold Storage. Tag names are invented.
Errors and limits
Consumer IoT standards do not automatically apply to industrial devices; use them as reference questions. Loop diagrams simplify; real systems have cascades and interlocks.
Exercises
- EX028 — Three attack points on the Freezer-2 loop. Name one per element: sensor, controller, actuator. Rubric: 3 = three plausible points; 2 = two; 1 = one; 0 = none.
- EX029 — Choosing a buying checklist. Which document would you use to write purchase questions for new temperature loggers? Rubric: 3 = ETSI EN 303 645 (or NIST IR 8259 for manufacturer activities) with reason; 2 = name only; 1 = SP 800-82 only; 0 = none.
- EX030 — Why loggers help integrity. Explain how the cloud loggers reduce the impact of a falsified TT-F2 reading. Rubric: 3 = independent measurement path reveals disagreement; 2 = partial; 1 = vague; 0 = none.
Synthesis
Orientation means seeing the physical loop, knowing which guidance fits which role, and keeping safety systems out of security side effects.
Continue studying — chapter 10 of 30
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