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3.1.5OFFICIAL STATEMENT BELOWDERIVED REQUIREMENTPENDING NIST SME REVIEW

3.1.5 — Least privilege

3.1 Access Control · NIST SP 800-171 Rev. 2 · The heading label is this site's navigational shorthand; the official language is the statement below.

Official requirement statement (verbatim)

Employ the principle of least privilege, including for specific security functions and privileged accounts.

NIST SP 800-171 Rev. 2 — Protecting CUI in Nonfederal Systems ↗NIST SP 800-171A — Assessing Security Requirements for CUI ↗
Independent interpretation

What this requirement is after

Every account, process, and privilege grant carries the minimum it needs and nothing more — with special care for security functions and privileged accounts. Standing local admin for everyone and a domain admin account used for daily work are the two most common ways small environments fail this.

Across revisions

Rev. 3 distributes least privilege across three requirements: the principle itself (03.01.05), non-privileged account use (03.01.06), and privileged functions (03.01.07).

Mapped practices

Brilliant at the Basics practices that support this requirement

Partial implementation supportModerate confidence

Why: Individual least-privilege access on OT platforms, engineering functions held to authorized staff, and standing vendor accounts driven to zero are the principle of least privilege enacted on production systems.

What this does not claim: Holds only for OT systems inside the CUI boundary. The requirement's weight in most assessments falls on the IT estate — privileged account separation, security function restriction, admin group review — none of which this OT-focused practice performs; those need their own implementation and evidence.

Practice-side activities
  • Grant individuals the minimum OT access their role requires, where platforms support distinct roles
  • Provision vendor access per engagement and revoke it afterward rather than leaving standing accounts
  • Review who holds engineering-level access on a cadence
Evidence this produces
  • OT access reviews showing removals and role reductions
  • Vendor account provisioning and revocation records per engagement

Where this holds: Holds only for OT systems within the organization's CUI boundary.

Review status: Technical review complete · Reviewed by inDirectIT practitioner review — CUI security and NIST SP 800-171 engineering · updated 2026-08-06

Doing the work

Implementation considerations and evidence

Implementation considerationsIndependent guidance — tailor to your environment
  • Remove standing local administrator rights from daily-driver accounts and grant elevation deliberately where a task requires it.
  • Keep privileged accounts separate, few, and enumerated — a list of who holds what privilege, reviewed on a cadence.
  • Apply the same discipline to service accounts and security tooling, which tend to accumulate broad rights nobody revisits.
What operating evidence looks likeRecords worth retaining, not a submission checklist
  • Privileged group membership exports with a justification per member
  • Dated privileged-access reviews showing removals actually happen
  • Configuration showing daily accounts without standing administrative rights

Suggested owners, derived from the mapped practices and artifacts: Plant / OT leader · Identity admin. Ownership is a named person in your organization, not a role on a website.

Artifacts

Templates and worksheets with a mapped relationship

INVENTORY · REVIEW QUARTERLYPrivileged Account Inventory
The other revision

Where this lands in Rev. 3

Provenance

Sources and review status

Primary sourcesNIST SP 800-171 Rev. 2 — Protecting CUI in Nonfederal Systems · NIST SP 800-171A — Assessing Security Requirements for CUI
Review statusPending NIST SME review
Content version1.0
Updated