03.13.16E — System Partitioning

Official NIST requirement content

Security requirement

Partition the system into [Organization-defined: SELECTED PARAMETER VALUE] residing in separate [Organization-defined: system components] domains or environments based on [Organization-defined: circumstances].

Official NIST discussion

Discussion

System partitioning is part of a defense-in-depth protection strategy. Organizations determine the degree of physical separation of system components. Physical separation options include physically distinct components in separate racks in the same room, critical components in separate rooms, and geographical separation of critical components. Managed interfaces restrict or prohibit network access and information flow among partitioned system components. This requirement does not enhance a specific requirement in SP 800-171 but can be used to strengthen the protection of CUI associated with critical programs or high value assets.

Official organization-defined parameters

Tailoring decisions required

Resolve these values through the governing organization’s approved tailoring and risk-management process before declaring the requirement implemented.

system componentsorganization-defined system componentssystem components to reside in separate physical or logical domains or environments based on circumstances for the physical or logical separation of components are defined.

SELECTED PARAMETER VALUE

circumstancesorganization-defined circumstances for physical or logical separation of componentscircumstances for the physical or logical separation of components are defined.

Official protection strategy classifications

Protection strategies supported

These classifications are carried from the official SP 800-172 OSCAL record and help explain the enhanced requirement’s defensive purpose.

PS-DLODamage-Limiting Operations

PS-PRAPenetration-Resistant Architecture

Bare Metal Cyber interpretation

Implementation perspective

Treat System Partitioning as an enhanced CUI protection outcome for elevated threat conditions that must be reflected in the system boundary, documented implementation, operational behavior, and assessment evidence. Pay particular attention to secure architecture, boundary protection, communications security, cryptography, and isolation of CUI processing.

Confirm the federal agency selected this enhanced requirement for the critical program or high-value asset and identify the CUI system components, services, users, and external connections in scope.
Resolve every organization-defined parameter through an approved governance and tailoring process.
Map each clause of the requirement to an accountable owner, implementation mechanism, and evidence source.
Verify that inherited and shared implementations are supported by current provider evidence and responsibility boundaries.
Collect evidence during normal operation and review changes, exceptions, and deficiencies on a risk-based cadence.

Questions to ask

Which critical-program or high-value-asset CUI, data flows, users, and services are protected by this enhanced requirement?
Which portions are implemented locally, inherited, shared, or not applicable, and what evidence supports that determination?
Do the system security plan, deployed configuration, operating process, and assessment evidence tell the same story?
What change, incident, or threshold should trigger reassessment?

Evidence and validation

network and trust-boundary diagrams
firewall and gateway configurations
cryptographic configuration and key records
segmentation and isolation test results

Common failure patterns

diagrams omitting cloud and third-party paths
encryption enabled without key governance
flat trust zones permitting unnecessary lateral movement
boundary rules accumulating without owner review

Official NIST SP 800-172A content

Assessment objectives and methods

Assessment objectives (1)

the system is partitioned into [Organization-defined: system components] residing in separate [Organization-defined: SELECTED PARAMETER VALUE] security domains or environments based on [Organization-defined: circumstances].

Examine

System and communications protection policy
procedures addressing system partitioning
system design documentation
system configuration settings and associated documentation
system architecture
list of system physical domains (or environments)
system facility diagrams
system network diagrams
system security plan
other relevant documents or records

Interview

System/network administrators
organizational personnel with information security responsibilities
organizational personnel installing, configuring, and/or maintaining the system
system developers/integrators

Test

Mechanisms supporting and/or implementing the physical separation of system components

Official source-control relationships

Source NIST SP 800-53 controls

These controls are referenced by the official SP 800-172 Rev. 3 OSCAL record. Open the corresponding control pages for complete control text, enhancements, D3FEND mappings, and related learning.

Source controlSC-32Open SP 800-53 control →

Source record

Authoritative sources

Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. The official publications, the responsible federal agency, and the governing contract or agreement determine applicability, tailoring, assessment depth, and required implementation.