# NIST SP 800-53 Rev. 5 SC-7(18) — Fail Secure - Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-7-18-fail-secure - Section: [Compliance](https://support.icompaas.com/compliance) › [NIST SP 800-53 Rev. 5 Controls](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5) › SC — System and Communications Protection - Last updated: 2026-06-05 - Publisher: iCompaas, Inc. (https://www.icompaas.com) **NIST SP 800-53 Rev. 5**·Control `SC-7(18)`·critical·Component: **System and Communications Protection** ## What this control requires > Prevent systems from entering unsecure states in the event of an operational failure of a boundary protection device. This is achieved by ensuring that devices like routers, firewalls, and application gateways fail in a secure manner, maintaining security properties even during failures, preventing unauthorized information access or releases. This control supports the Boundary Protection Device capability within the System and Communications Protection family. > > — NIST SP 800-53 Rev. 5, Control SC-7(18) ### In plain English Prevent systems from entering unsecure states in the event of an operational failure of a boundary protection device. In practice, this means you can prove you access management-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 **critical** in the source catalogue. Treat gaps here as production incidents in the risk register, not housekeeping. ## 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-7(18)) and look for objective evidence on the latest two assessment cycles. ## How to implement #### Cloud Posture **CSPM.** Run Wiz / Prisma / Defender for Cloud / Security Command Center over every account; auto-ticket findings above your accepted-risk threshold. #### Configuration Management **Policy-as-code.** Codify the control as Service Control Policies (AWS), Azure Policy initiatives, or Organisation Policy (GCP) so the platform enforces what the document promises. **IaC.** Gate Terraform / Pulumi / CloudFormation changes with Checkov / tfsec / OPA so misconfigurations never reach production. **Drift.** Run a CSPM (Wiz / Prisma / Defender for Cloud / Security Command Center) over every account and route findings to a single risk register. #### 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. ### Operational checklist - **Access.** Document the trigger, the owner and the cadence. - **Information.** Document the trigger, the owner and the cadence. - **Security.** Document the trigger, the owner and the cadence. - **Configuration.** Document the trigger, the owner and the cadence. - **Fail.** Document the trigger, the owner and the cadence. - **Scope:** management, information, system, application, failure, protection, configuration, capability. ## Evidence to collect - **Infra Scan.** Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings. Infrastructure posture tooling (AWS Config, Azure Policy, Nessus) verifies platform hardening. Focus: Fail Secure. ## Common pitfalls - Treating CSPM findings as a backlog instead of a hot queue: findings older than the policy SLA accumulate until the auditor asks why. - Manual cloud-console changes that never make it back to Terraform — drift accumulates until the next outage forces a reconciliation. - Default-allow egress rules; East-West traffic with no segmentation; jump hosts on the public internet with password auth. - Pilot MDM rollouts that quietly exclude executives or engineers; carving out the highest-risk users is the most common audit failure. ## How it maps to other frameworks Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit. - [**NIST SP 800-171 Rev. 3 3.14.6** — System Monitoring](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-14-6-system-monitoring) - [**ISO/IEC 27001:2022 A.8.22** — Segregation of networks](https://support.icompaas.com/compliance/iso-27001-2022/a-8-22-segregation-of-networks) - [**BSI C5:2020 COS-05** — Networks for administration](https://support.icompaas.com/compliance/bsi-c5-2020/cos-05-networks-for-administration) ## Related controls in NIST SP 800-53 Rev. 5 - [**Control SC-7(26)** — Classified National Security System Connections](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-7-26-classified-national-security-system-connections) - [**Control SC-7(25)** — Unclassified National Security System Connections](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-7-25-unclassified-national-security-system-connections) - [**Control SC-7(27)** — Unclassified Non-National Security System Connections](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-7-27-unclassified-non-national-security-system-connections) - [**Control SC-7(5)** — Deny By Default -- Allow By Exception](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-7-5-deny-by-default-allow-by-exception) - [**Control SC-7(22)** — Separate Subnets For Connecting To Different Security Domains](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-7-22-separate-subnets-for-connecting-to-different-security-domains) - [**Control SC-10** — Network Disconnect](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-10-network-disconnect) ## References - [NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5](https://csrc.nist.gov/Projects/risk-management/sp800-53-controls) - Catalogue identifier: `Control SC-7(18)` Topics: network securitycloud postureconfiguration managementendpoint protection ## Related compliance guidance - [NIST SP 800-53 Rev. 5: a practical implementation guide for cloud teams](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5): Start with the full NIST SP 800-53 implementation guide — scope, roadmap, evidence and how the assessment runs. - [NIST SP 800-171 and CMMC: a practical guide to protecting CUI in the cloud](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3): If your obligation is protecting CUI in your own systems for a federal or defence contract, this derived subset — not the full catalogue — is the requirement. - [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Most commercial SaaS already hold a SOC 2 Type 2, and FedRAMP 20x Class A is designed for providers that have one.