NIST SP 800-53 Rev. 5·Control SC-37·high·Component: System and Communications Protection

What this control requires

Use out-of-band channels for the physical delivery or electronic transmission of organization-defined information, system components, or devices to specified individuals or systems. These channels, such as non-network accesses or separate network paths, ensure confidentiality, integrity, and availability, as they are less vulnerable than in-band channels that carry operational traffic. This control supports the Out-of-Band Communication System capability within the System and Communications Protection family.
— NIST SP 800-53 Rev. 5, Control SC-37

In plain English

Use out-of-band channels for the physical delivery or electronic transmission of organization-defined information, system components, or devices to specified individuals or systems. In practice, this means you can prove you information information-level controls on a defined cadence.

Why it matters

SP 800-53 is the catalogue every U.S. federal authorisation (FedRAMP, FISMA, CMMC) and most regulated industries point at. A missing control surfaces as a Plan of Action & Milestones (POA&M) item that an Authorizing Official must approve before the Authority To Operate is granted or renewed.

This control is rated high. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation.

What an auditor looks for

A 3PAO (FedRAMP) or Independent Assessor (NIST RMF) tests against NIST SP 800-53A assessment procedures. For each control they expect a documented implementation that addresses every assessment objective (Examine, Interview, Test) and an implementation summary in the System Security Plan.

Within System and Communications Protection, the assessor will trace your implementation back to the catalogue reference (Control SC-37) and look for objective evidence on the latest two assessment cycles.

How to implement

Endpoint Protection

MDM. Make MDM enrollment a hard gate for device access (Intune compliance + Conditional Access, or Jamf + Okta device trust). Unmanaged devices simply don't get a session token.

EDR. Deploy CrowdStrike / SentinelOne / Defender for Endpoint to every server and laptop; alert on any host that stops sending telemetry for >24h.

Network Security

AWS. VPC Flow Logs to S3, default-deny security groups, AWS Network Firewall for north-south, and Transit Gateway for hub-and-spoke segmentation.

Azure. NSGs with deny-by-default, Azure Firewall Premium with TLS inspection, Private Endpoints for PaaS, and Microsoft Defender for Cloud's secure score for drift.

GCP. VPC Service Controls perimeters around sensitive APIs, Cloud NGFW Enterprise for L7 inspection, Private Service Connect for managed services.

Physical Security

Inheritance. For cloud-only operations, inherit physical controls from the provider's SOC 2 / ISO 27001 report and document the inheritance in the SoA.

Operational checklist

  • Information. Document the trigger, the owner and the cadence.
  • Security. Document the trigger, the owner and the cadence.
  • Physical. Document the trigger, the owner and the cadence.
  • Network. Document the trigger, the owner and the cadence.
  • Separate. Document the trigger, the owner and the cadence.
  • Scope: information, organization, system, protection, components, capability, systems, transmission.

Evidence to collect

  • User Device Scan. MDM compliance state per user device (Intune / Jamf / Workspace ONE).

Endpoint compliance telemetry (Intune, Jamf) proves managed coverage. Focus: Out-Of-Band Channels.

Common pitfalls

  • Pilot MDM rollouts that quietly exclude executives or engineers; carving out the highest-risk users is the most common audit failure.
  • Default-allow egress rules; East-West traffic with no segmentation; jump hosts on the public internet with password auth.

Related controls in NIST SP 800-53 Rev. 5

References

Topics: endpoint securityendpoint protectionnetwork securityphysical security