Definition
Restricting unauthorized changes to the operating mode prevents devices from switching into inappropriate or vulnerable states during normal use.
How it works
Many OT Controllers use key switches to change the controller into different modes of operation. These modes of operation can include Program, Run, Remote, or Stop.
The key switch should be left in the appropriate key switch position, e.g., run or remote during normal operations.
Implement a key management procedure to include removing the physical key from the key switch when not in use.
Implementation perspective
Operating Mode Restriction should be treated as a technical defensive capability rather than a product checkbox. In practice, teams should define the protected scope, the conditions under which the technique acts, and the observable evidence that demonstrates the intended behavior. For this technique, likely engineering context includes OT Controller Operating Mode.
Use the technique to create a logical or physical boundary that limits access, execution, communication, or movement.
Questions to ask
- What is being isolated, from whom or what, and under which conditions?
- Which flows or operations remain explicitly allowed across the boundary?
- What happens when the isolation mechanism fails or loses policy context?
- How is the boundary tested for alternate paths, bypasses, and unintended dependencies?
Evidence and validation
- Architecture and data-flow diagrams showing the isolation boundary
- Policy, rule, or configuration exports from enforcing components
- Tests of allowed, denied, and failure-state behavior
- Monitoring evidence for boundary violations and policy changes
Common failure patterns
- The intended boundary has undocumented alternate paths or inherited trust relationships.
- Rules accumulate without ownership, review, or removal of obsolete exceptions.
- Isolation is assumed from network location while application, identity, or management paths remain open.
This implementation perspective is original Bare Metal Cyber educational content. It does not replace the official D3FEND definition or establish that a specific product implements the technique.
Technique hierarchy
Top-level family
Parent techniques
Direct child techniques
None listed at this level.
Artifacts and ontology entities
These relationships describe how D3FEND connects a defensive technique to artifacts or other ontology entities. They describe graph semantics, not a product certification.
Explicit technique relationships
Show inferred artifact relationship paths (1)
Offensive-technique relationships
These relationships are generated from D3FEND graph paths and are explicitly experimental. They should be treated as hypotheses for defensive analysis—not as proof that the technique prevents, detects, or removes an offensive behavior.
ATT&CK for ICS (2)
Authoritative sources
- Open this technique on the official D3FEND website ↗
- Open the official ontology resources ↗
- MITRE ATT&CK - Authorization Enforcement ↗MITRE · ExternalKnowledgeBase
- TRITON Malware Remains Threat to Global Critical Infrastructure Industrial Control Systems (ICS) ↗FBI · InternetArticleReference
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