SC-7(5)

Requirement

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

Discussion

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.

NIST 800-53A Assessment Guidance

Examine

[SELECT FROM: System and communications protection policy; procedures addressing boundary protection; system design documentation; system configuration settings and associated documentation; system audit records; system security plan; other relevant documents or records].

Interview

[SELECT FROM: System/network administrators; organizational personnel with information security responsibilities; system developer; organizational personnel with boundary protection responsibilities].

Test

[SELECT FROM: Mechanisms implementing traffic management at managed interfaces].

ID	Assessment Objectives
SC-07(05)[01]	network communications traffic is denied by default <SC-07(05)_ODP[01] SELECTED PARAMETER VALUES>;
SC-07(05)[02]	network communications traffic is allowed by exception <SC-07(05)_ODP[01] SELECTED PARAMETER VALUES>.

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