Essentials for OT
PRO-19 Operational technology isolation
Be ready to isolate vital OT from other networks and keep it running safely for a set period. Use buffer networks (DMZs) at OT's edges, document and check isolation, and manage it only from inside vital OT. Make the services vital OT needs work on their own.
Reviewed 18 October 2026 · Current to ASD's Essentials for OT, published 15 October 2026
The principle
Operational technology systems (infrastructure) are logically and physically isolated from information technology systems (infrastructure) and all external infrastructure, with only authorised, controlled and monitored communication paths between systems permitted.
The five actions
ASD's actions are quoted as published in Essentials for OT. ASD has not given them IDs, so they are numbered by position.
Action 1 of 5
Establish and maintain demilitarised zones that isolate OT at its perimeters from all networks not under the organisation's sole administrative control.
In plain English: Set up and keep buffer networks (DMZs) at OT's edges. Use them to isolate OT from every network not under your organisation's sole admin control.
- Domains
- Boundary services
- MITRE ATT&CK
- External remote services
- Exploitation of remote services
- Internet accessible device
Action 2 of 5
Document the procedures used to enact isolation, including clear physical identification of the cables and equipment involved.
In plain English: Write down the steps for isolating OT, including clear physical marking of the cables and equipment involved.
- Domains
- Critical processes and services
- Boundary services
Action 3 of 5
Ensure isolation points can only be managed from within vital OT, so that enacted isolation cannot be reversed externally.
In plain English: Make sure isolation points can only be managed from inside vital OT. Then no one outside can undo an isolation once it is in place.
- Domains
- Boundary services
- MITRE ATT&CK
- External remote services
- Remote services
- Valid accounts
Action 4 of 5
Maintain the capability to isolate vital OT and sustain safe operation for a defined period aligned to critical service continuity requirements, and verify the effectiveness of isolation mechanisms on enactment and throughout the isolation period.
In plain English: Be able to isolate vital OT and run it safely for a set period that matches critical service continuity needs. Check isolation works when it starts and throughout.
- Domains
- Critical processes and services
- Boundary services
- MITRE ATT&CK
- Lateral tool transfer
- Remote services
- Connection proxy
Action 5 of 5
Ensure the services on which vital OT depends operate independently of systems outside the OT environment, using separate software, credentials, storage, policy and servers, so that those services remain available throughout isolation.
In plain English: Run the services vital OT depends on without relying on systems outside OT. Give them their own software, credentials, storage, policy and servers so they work throughout isolation.
- Domains
- Critical processes and services
- Boundary services
- Identity services
- Business systems
- MITRE ATT&CK
- Loss of availability
- Loss of control
- Loss of view
See all 34 principles in Essentials for OT, or read our OT guide.
Sources
The ASD publications this page quotes.
Quoted ASD material © Commonwealth of Australia 2026, licensed under CC BY 4.0.
MITRE ATT&CK® technique names and IDs: © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. See MITRE's ATT&CK terms of use.
Everything else on this page is written by Control Stack.