# NIST SP 800-53 Rev. 5 SC-3(3) — Minimize Nonsecurity Functionality - Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-3-3-minimize-nonsecurity-functionality - 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(3)`·high·Component: **System and Communications Protection** ## What this control requires > Minimize the number of nonsecurity functions within the isolation boundary containing security functions. This reduces trusted code size, limits risk from errors or malicious code, and improves understandability of security enforcement. This control supports the Isolation Boundary Minimization Protocol capability within the System and Communications Protection family. > > — NIST SP 800-53 Rev. 5, Control SC-3(3) ### In plain English Minimize the number of nonsecurity functions within the isolation boundary containing security functions. In practice, this means you can prove you security enforcement-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(3)) and look for objective evidence on the latest two assessment cycles. ## How to implement #### Secure Development **Pipeline.** Require code review, SAST (Semgrep / Snyk Code), SCA (Dependabot / Renovate), secret-scanning and IaC scanning in the merge pipeline. **Branch protection.** Protected branches enforce reviews, signed commits and passing CI before merge; document the protection rules as the control evidence. #### Code Review Testing **Pipeline.** Require at least one human reviewer plus passing CI (lint, type, unit, security scan) before merge — protected branches enforce this. ### Operational checklist - **Security.** Document the trigger, the owner and the cadence. - **Review.** Document the trigger, the owner and the cadence. - **Protection.** Document the trigger, the owner and the cadence. - **Limits.** Document the trigger, the owner and the cadence. - **System.** Document the trigger, the owner and the cadence. - **Scope:** enforcement, system, application, functions, protection, functionality, review, capability. ## Evidence to collect - **Code Repo Scan.** Source-control evidence — branch protection, required reviewers, CI status, SCA / SAST reports. Source control pipelines (GitHub, GitLab) enforce SDLC guardrails. Focus: Minimize Nonsecurity Functionality. ## Common pitfalls - CI security checks set to warn-only; the merge button is faster than the security feedback. ## 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 3.14.2** — Malicious Code Protection](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-14-2-malicious-code-protection) - [**CIS Controls v8 16.12** — Implement Code-Level Security Checks](https://support.icompaas.com/compliance/cis-controls-v8/16-12-implement-code-level-security-checks) ## Related controls in NIST SP 800-53 Rev. 5 - [**Control SC-26** — Decoys](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-26-decoys) - [**Control SC-7(9)** — Restrict Threatening Outgoing Communications Traffic](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-7-9-restrict-threatening-outgoing-communications-traffic) - [**Control SC-18(5)** — Allow Execution Only In Confined Environments](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-18-5-allow-execution-only-in-confined-environments) - [**Control SC-35** — External Malicious Code Identification](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-35-external-malicious-code-identification) - [**Control MA-3** — Maintenance Tools](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ma-3-maintenance-tools) - [**Control AT-2(4)** — Suspicious Communications And Anomalous System Behavior](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/at-2-4-suspicious-communications-and-anomalous-system-behavior) ## 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(3)` Topics: application securitysecure developmentcode review testingdevsecops ## 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.