# NIST SP 800-53 Rev. 5 SC-3(4) — Module Coupling And Cohesiveness - Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-3-4-module-coupling-and-cohesiveness - 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-3(4)`·high·Component: **System and Communications Protection** ## What this control requires > Implement security functions as largely independent modules that maximize internal cohesiveness and minimize coupling. Use layering, minimization, and modular decomposition to reduce complexity and constrain interactions. This control supports the Modular Isolation and Design Integrity Framework capability within the System and Communications Protection family. > > — NIST SP 800-53 Rev. 5, Control SC-3(4) ### In plain English Implement security functions as largely independent modules that maximize internal cohesiveness and minimize coupling. In practice, this means you can prove you policy 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 **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-3(4)) and look for objective evidence on the latest two assessment cycles. ## How to implement #### Policy Management **Docs.** Keep each policy in version-controlled Markdown alongside the code that implements it; ship a signed PDF snapshot at each annual review and link the SHA into the SoA. ### Operational checklist - **Policy.** Document the trigger, the owner and the cadence. - **Security.** Document the trigger, the owner and the cadence. - **Decomposition.** Document the trigger, the owner and the cadence. - **Internal.** Document the trigger, the owner and the cadence. - **Protection.** Document the trigger, the owner and the cadence. - **Scope:** management, system, functions, protection, capability, implement, policy, integrity. ## Evidence to collect - **Policy Document.** A signed and version-controlled policy / standard / procedure document. Signed policy or standard documents the safeguard. Focus: Module Coupling And Cohesiveness. ## Common pitfalls - Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced. ## 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. - [**HIPAA (45 CFR Part 164) 164.312(e)(2)(i)** — Transmission Security - Integrity Controls](https://support.icompaas.com/compliance/hipaa/164-312-e-2-i-transmission-security-integrity-controls) - [**NIST SP 800-171 Rev. 3 3.14.3** — Security Alerts, Advisories, and Directives](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-14-3-security-alerts-advisories-and-directives) - [**BSI C5:2020 SP-01** — Documentation, communication and provision of policies and instructions](https://support.icompaas.com/compliance/bsi-c5-2020/sp-01-documentation-communication-and-provision-of-policies-and-instructions) ## Related controls in NIST SP 800-53 Rev. 5 - [**Control SC-3(5)** — Layered Structures](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-3-5-layered-structures) - [**Control SC-39(2)** — Separate Execution Domain Per Thread](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-39-2-separate-execution-domain-per-thread) - [**Control SC-3(1)** — Hardware Separation](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-3-1-hardware-separation) - [**Control SC-39** — Process Isolation](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-39-process-isolation) - [**Control SC-16(1)** — Integrity Verification](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-16-1-integrity-verification) - [**Control SC-46** — Cross Domain Policy Enforcement](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-46-cross-domain-policy-enforcement) ## 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-3(4)` Topics: governance riskpolicy management ## 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.