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SC-7(18) SC · System and Communications Protection

Fail Secure

LOW MODERATE ✓ HIGH
1 Overlay 3 Related Controls
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Requirements NIST SOURCE

Prevent systems from entering unsecure states in the event of an operational failure of a boundary protection device.

Discussion (NIST Supplemental Guidance)

Fail secure is a condition achieved by employing mechanisms to ensure that in the event of operational failures of boundary protection devices at managed interfaces, systems do not enter into unsecure states where intended security properties no longer hold. Managed interfaces include routers, firewalls, and application gateways that reside on protected subnetworks (commonly referred to as demilitarized zones). Failures of boundary protection devices cannot lead to or cause information external to the devices to enter the devices nor can failures permit unauthorized information releases.

Implementation Guidance

Engineering Interpretation

Original engineering commentary written for this explorer — not NIST source text and not authoritative guidance.

No engineering interpretation has been authored for SC-7(18) yet. This section is architected to receive it — see the Requirements and Assessment sections above for the authoritative NIST source content in the meantime.

Assessment

NIST SP 800-53A REV 5.2.0

Assessment Objectives

  1. systems are prevented from entering unsecure states in the event of an operational failure of a boundary protection device.

Examine

[SELECT FROM: System and communications protection policy; procedures addressing boundary protection; system design documentation; system architecture; 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 supporting and/or implementing secure failure].

Overlays

Showing the OT/ICS overlay for the parent control SC-7 — see the SC-7(18) entries within each baseline below.

OT/ICS Overlay SP 800-82r3

NIST SP 800-82r3 Appendix F, Table 22. Blank baseline means the control/control enhancement is not selected in that initial OT baseline.

LOW

  • Base control: Included (matches standard baseline)
  • Added: (28) (29)

MODERATE

  • Base control: Included (matches standard baseline)
  • Included: (3) (4) (5) (7) (8)
  • Added: (18) (28) (29)

HIGH

  • Base control: Included (matches standard baseline)
  • Included: (3) (4) (5) (7) (8) (18) (21)
  • Added: (28) (29)

STIGs & CCIs

No STIG checks or CCI mappings are currently loaded for SC-7(18). This section is architected to display, per product: STIG ID, Finding ID, Severity, Title, Description, Check, Fix, CCI, and NIST control mapping — but nothing is populated here until a real DISA STIG/CCI dataset is ingested.

Learn more about STIG/CCI integration →

Evidence

Potential Evidence — Derived

Categorized from the SP 800-53A "Examine"/"Test" artifact list above by keyword — not an authoritative NIST evidence list.

Policy

  • System and communications protection policy
  • system security plan

Configuration

  • system design documentation
  • system architecture
  • system configuration settings and associated documentation

Testing

  • Mechanisms supporting and/or implementing secure failure

Other Records

  • procedures addressing boundary protection
  • system audit records
  • other relevant documents or records