authorization boundary

An authorization boundary is the formally defined scope of information system components, services, and data flows that are treated as a single system for security assessment and authorization. It identifies what is included in a given authorization decision and, just as importantly, what is outside that scope.

Key characteristics

In industrial and regulated environments, an authorization boundary commonly:

• Groups hardware, software, cloud services, and networks that are managed and assessed as one information system
• Defines where data enters and leaves that system, including interfaces to OT, MES, ERP, and partner systems
• Clarifies which components and data are covered by a specific security baseline or framework (for example, FedRAMP, NIST-based controls, or internal policies)
• Separates in-scope elements (subject to specific controls and evidence) from out-of-scope elements that might be covered by other authorizations or contracts

For cloud and hybrid manufacturing systems, an authorization boundary may encompass:

• A SaaS or IaaS environment used to store production, quality, or maintenance data
• Application servers, databases, and middleware running in a specific cloud tenant
• Secure connections to plant networks, MES, LIMS, historians, or data lakes
• Management and monitoring components used to operate that environment

Operational meaning

Defining the authorization boundary is an early and foundational step in security and compliance planning. It:

• Determines which assets must be inventoried, documented, and assessed
• Guides which technical, administrative, and physical controls are applicable
• Shapes architecture decisions, such as where to place gateways, firewalls, and data brokers between IT and OT networks
• Helps align roles and responsibilities between internal teams and external providers

In plants that rely on validated systems or controlled OT environments, a clear authorization boundary helps show how cloud services are segmented from safety-critical control systems while still allowing data exchange.

Relation to FedRAMP and similar frameworks

In U.S. federal cloud contexts, such as FedRAMP Moderate or High, the authorization boundary describes the cloud service and supporting infrastructure that are evaluated against a defined control baseline. Interfaces to external agency systems, on-premises OT systems, or third-party services are documented as connections across that boundary, with their own responsibilities and controls.

Common confusion

• Authorization boundary vs. system boundary: In many frameworks, these terms are closely related and sometimes used interchangeably. “Authorization boundary” emphasizes the scope of a formal authorization decision; “system boundary” emphasizes the technical perimeter of the system itself.
• Authorization boundary vs. network boundary: A network boundary is typically a technical segmentation point (for example, a firewall between IT and OT networks). An authorization boundary may be broader or different, and is defined for governance and assessment, not only for routing or firewall configuration.