# NIST SP 800-53 Rev. 5 SC-35 — External Malicious Code Identification - Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-35-external-malicious-code-identification - 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-35`·high·Component: **System and Communications Protection** ## What this control requires > Include system components that proactively identify network-based malicious code or malicious websites. Unlike decoys, these components actively probe networks, including the Internet, to detect malicious code on external websites. Virtualization is commonly used to isolate discovered malicious code and prevent it from infecting organizational systems. This control supports the Malicious Code Detection System capability within the System and Communications Protection family. > > — NIST SP 800-53 Rev. 5, Control SC-35 ### In plain English Include system components that proactively identify network-based malicious code or malicious websites. In practice, this means you can prove you security system-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-35) 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. #### 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 - **Security.** Document the trigger, the owner and the cadence. - **Detection.** Document the trigger, the owner and the cadence. - **Network.** 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. - **Scope:** system, application, virtualization, protection, review, components, capability, networks. ## 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: External Malicious Code Identification. ## Common pitfalls - CI security checks set to warn-only; the merge button is faster than the security feedback. - Default-allow egress rules; East-West traffic with no segmentation; jump hosts on the public internet with password auth. ## 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) ## Related controls in NIST SP 800-53 Rev. 5 - [**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-26** — Decoys](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-26-decoys) - [**Control SC-3(3)** — Minimize Nonsecurity Functionality](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/sc-3-3-minimize-nonsecurity-functionality) - [**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) - [**Control MA-3** — Maintenance Tools](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ma-3-maintenance-tools) ## 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-35` Topics: application securitysecure developmentcode review testingdevsecopsnetwork security ## 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.