SC-7(5): Deny by Default – Allow by Exception

CSF v1.1 References:

Threats Addressed:


  • Moderate
  • High

Previous Version:

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Incorporates the following control from the previous version of the control set: CA-3(5): Restrictions On External System Connections.

Control Statement

Deny network communications traffic by default and allow network communications traffic by exception [Assignment (one or more): at managed interfaces, for [Assignment: organization-defined systems] ].

Supplemental Guidance

Denying by default and allowing by exception applies to inbound and outbound network communications traffic. A deny-all, permit-by-exception network communications traffic policy ensures that only those system connections that are essential and approved are allowed. Deny by default, allow by exception also applies to a system that is connected to an external system.