# NIST SP 800-171 Rev. 3 3.4.8 — Authorized Software - Allow by Exception - Source: https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-4-8-authorized-software-allow-by-exception - Section: [Compliance](https://support.icompaas.com/compliance) › [NIST SP 800-171 Rev. 3 Requirements](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3) › Configuration Management — §3.4 - Last updated: 2026-06-05 - Publisher: iCompaas, Inc. (https://www.icompaas.com) **NIST SP 800-171 Rev. 3**·Requirement `3.4.8`·high·Component: **Configuration Management** ## What this control requires > This control establishes a policy for identifying authorized software programs and implementing a deny-all, allow-by-exception policy for executing software on the system. It mandates reviewing and updating the list of authorized software programs at a defined frequency. This ensures that only approved software is allowed, preventing unauthorized software from running on the system. This control supports the Software Authorization capability within the Configuration Management (3.4) family. > > — NIST SP 800-171 Rev. 3, Requirement 3.4.8 ### In plain English This control establishes a policy for identifying authorized software programs and implementing a deny-all, allow-by-exception policy for executing software on the system. In practice, this means you can prove you configuration management-level controls on a defined cadence. ## Why it matters DoD contractors and their subcontractors must implement all 100 SP 800-171 requirements to keep CUI handling contracts. Gaps are scored against the SPRS scoring methodology; below a 110-point starting score, each unmet requirement deducts points and a below-threshold score can disqualify a bid. 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 C3PAO conducting a CMMC Level 2 assessment uses NIST SP 800-171A objectives. They expect a System Security Plan (SSP), Plan of Action & Milestones (POA&M) for any gaps, and objective evidence (configurations, ticket records, training records) for every requirement. Within **Configuration Management**, the assessor will trace your implementation back to the catalogue reference (Requirement 3.4.8) 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 - **Configuration.** Document the trigger, the owner and the cadence. - **Authorized.** Document the trigger, the owner and the cadence. - **System.** Document the trigger, the owner and the cadence. - **Risk.** Document the trigger, the owner and the cadence. - **Policy.** Document the trigger, the owner and the cadence. - **Scope:** management, configuration, software, authorization. ## Evidence to collect - **Policy Document.** A signed and version-controlled policy / standard / procedure document. Signed policy or standard documents the safeguard. Focus: Authorized Software - Allow by Exception. ## 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. - [**ISO/IEC 27001:2022 A.8.19** — Installation of software on operational systems](https://support.icompaas.com/compliance/iso-27001-2022/a-8-19-installation-of-software-on-operational-systems) - [**NIST SP 800-53 Rev. 5 CM-11** — User-Installed Software](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/cm-11-user-installed-software) - [**CIS Controls v8 2.6** — Allowlist Authorized Libraries](https://support.icompaas.com/compliance/cis-controls-v8/2-6-allowlist-authorized-libraries) - [**SOC 2 (2017 TSC) CC2.3** — External Communication on Internal Control Matters](https://support.icompaas.com/compliance/soc-2-trust-services-criteria/cc2-3-external-communication-on-internal-control-matters) - [**HIPAA (45 CFR Part 164) 164.308(a)(3)(ii)(A)** — Workforce security - Authorization and/or Supervision](https://support.icompaas.com/compliance/hipaa/164-308-a-3-ii-a-workforce-security-authorization-and-or-supervision) ## Related controls in NIST SP 800-171 Rev. 3 - [**Requirement 3.4.4** — Impact Analyses](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-4-4-impact-analyses) - [**Requirement 3.4.11** — Information Location](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-4-11-information-location) - [**Requirement 3.7.6** — Maintenance Personnel](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-7-6-maintenance-personnel) - [**Requirement 3.13.2** — Recategorized as NCO](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-13-2-recategorized-as-nco) - [**Requirement 3.4.1** — Baseline Configuration](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-4-1-baseline-configuration) - [**Requirement 3.13.15** — Session Authenticity](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-13-15-session-authenticity) ## References - [NIST Computer Security Resource Center — NIST SP 800-171 Rev. 3](https://csrc.nist.gov/pubs/sp/800/171/r3/final) - Catalogue identifier: `Requirement 3.4.8` Topics: governance riskpolicy management ## Related compliance guidance - [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): Start with the full NIST SP 800-171 implementation guide — scope, roadmap, evidence and how the assessment runs. - [NIST SP 800-53 Rev. 5: a practical implementation guide for cloud teams](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5): The catalogue 800-171 is tailored from, and the basis of the FedRAMP Moderate baseline your cloud providers must meet for CUI. - [ISO/IEC 27001:2022 compliance: a practical implementation guide](https://support.icompaas.com/compliance/iso-27001-2022): If commercial customers ask for a certificate as well, most 800-171 controls can be evidenced once and mapped to Annex A.