Machine controller (PLC): what it is and how it is attacked
The small computer that tells a piece of machinery what to do.
Also known as
- PLC
- RTU
- programmable logic controller
Typing any of them into the editor finds this object.
Why it matters on a security diagram
It is the last step between a network instruction and something physical moving.
How it gets attacked, and what reduces it
How it gets attacked
- Instructions accepted without any check on who sent them
- Displays showing normal readings while the process is altered
What reduces it
- Restrict which systems may send it instructions, since it will not check who sent them
- Compare displayed readings against an independent source, because a display can be made to look normal
Where it sits
- Group
- Endpoints and devices · The things people and processes touch directly.
- Whose side, by default
- Ours · Belongs to the organisation the diagram is about.
- Catalogue identifier
- controller
Reviewed . CC BY 4.0.
Others in endpoints and devices
- Desktop computerworkstation · PC · desktopA computer somebody sits at to do their job.
- Laptopnotebook · mobile workstationA portable computer that leaves the building.
- Mobile phonesmartphone · mobile · handsetA pocket computer that reads company email.
- PrinterMFP · multifunction device · copierPrints, scans and often emails documents.
- Smart deviceIoT · internet of things · connected device · camera · CCTV · IP camera · security camera · sensor · door lock · smart TVEveryday equipment with a network connection: cameras, sensors, door locks, TVs.
- Plant equipmentOT · ICS · SCADA · operational technologyMachinery that runs a physical process: a pump, a valve, a production line.
- Door access readercard reader · badge reader · access controlReads a badge to unlock a door.
The endpoints and devices group lists all 8 of them side by side.
Machine controller on your own diagram
Open the editor, press N, and type PLC. The object is placed and connected to whatever was selected, and Tab adds the next one already joined to it. Nothing is uploaded: the page is served with a Content Security Policy that forbids the browser from making any outbound request at all.
Open the diagram maker