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NET-42.1: Isolation of System Components

NET 5 — Medium Protect

Mechanisms exist to employ boundary protections to isolate Technology Assets, Applications and/or Services (TAAS) that support critical missions and/or business functions.

Renumbered: Formerly NET-03.7 in SCF 2025.4.

Control Question: Does the organization employ boundary protections to isolate Technology Assets, Applications and/or Services (TAAS) that support critical missions and/or business functions?

General (18)
US (3)
Framework Mapping Values
USA Federal CMMC 2.0 Level 3 SC.L3-3.13.4E
USA Federal FedRAMP R5 (high) SC-07(21)
USA Federal TSA SDP 2021-02F III.D.4 III.F.1.d
EMEA (2)
Framework Mapping Values
EMEA EU DORA RTS 2024 Article 13.1(a)
EMEA Saudi Arabia ECC-1 2018 5-1-3-4
APAC (3)

Capability Maturity Model

Level 0 — Not Performed

Practices are non-existent, based on the inability to demonstrate an implemented and operational capability. A reasonable person would conclude the control is not being performed.

Level 1 — Performed Informally

SCR-CMM Level 1 criteria definitions are not available for this control: ▪ A reasonable person would conclude this control requires a structured process. ▪ At this level of maturity, the "ad hoc" nature of performing a capability informally would indicate the intent of the control is not met due to a lack of consistency and formality.

Level 2 — Planned & Tracked

Network Security (NET) capabilities are requirements-driven, but are not standardized across the entity (e.g., local/regional level consistency). Capability criteria associated with this control reasonably expect the following criteria to exist: ▪ Policies and standards associated with NET domain capabilities are formally documented and centrally-managed by the entity. ▪ Standardized Operating Procedures (SOP) associated with NET domain capabilities are documented and maintained by process owners. ▪ IT and/or cybersecurity personnel work with business stakeholders and process owners to appropriately scope and reasonably implement cybersecurity and data protection controls associated with NET domain capabilities to address applicable statutory, regulatory and/or contractual requirements for Technology Assets, Applications, Services and/or Data (TAASD). ▪ Network security-related controls are primarily administrative and preventative in nature (e.g., policies, standards and procedures & guidelines). ▪ Network security management may be a defined function (e.g., team or department) or assigned as an additional duty to existing IT and/or cybersecurity personnel. ▪ IT personnel define secure networking practices to protect the Confidentiality, Integrity, Availability and Safety (CIAS) of the organization's TAASD. ▪ Secure Baseline Configurations (SBC) enforce the principles of least privileges and least functionality for boundary protection technologies.

Level 3 — Well Defined

Network Security (NET) capabilities are standardized across the entity for applicability to People, Processes, Technologies, Data and/or Facilities (PPTDF) to ensure consistency for Technology Assets, Applications, Services and/or Data (TAASD). Capability criteria associated with this control reasonably expect the following criteria to exist: ▪ Policies and standards associated with NET domain capabilities are formally documented and centrally-managed by the entity's Governance, Risk & Compliance (GRC) team, or similar function. ▪ Standardized Operating Procedures (SOP) associated with NET domain capabilities are well-documented and kept current by process owners. ▪ A network security management team, or similar function, is appropriately staffed and supported to implement and maintain NET domain capabilities. ▪ Technology is leveraged to enhance the efficiency and accuracy of network security operations (e.g., network management solution and log aggregator). ▪ The entity's Governance, Risk & Compliance (GRC) team, or similar function, works with business stakeholders and process owners to appropriately scope and reasonably implement cybersecurity and data protection controls associated with NET domain capabilities to address Minimum Compliance Requirements (MCR) (e.g., applicable statutory, regulatory and/or contractual requirements) and Discretionary Security Requirements (DSR) (e.g., entity-required controls). ▪ Secure Baseline Configurations (SBC) enforce the principles of least privileges and least functionality for boundary protection technologies. ▪ An implemented and operational capability exists to employ boundary protections to isolate Technology Assets, Applications and/or Services (TAAS) that support critical missions and/or business functions.

Level 4 — Quantitatively Controlled

Utilize SCR-CMM Level 3 criteria definitions: ▪ There are no defined Level 4 criteria, since it is reasonable to assume a quantitatively-controlled process is not necessary to operationalize this control. ▪ While it may be possible to develop “metrics-driven” capabilities for this control, the criteria would be organization-specific to define.

Level 5 — Continuously Improving

Utilize SCR-CMM Level 3 or Level 4 (if available) criteria definitions: ▪ There are no defined Level 5 criteria, since it is reasonable to assume a continuously-improving process is not necessary to operationalize this control. ▪ Level 5 capabilities should be considered “world-class” where the control builds on Level 4 capabilities, but are continuously improving through Artificial Intelligence (AI) and/or Machine Learning (ML) technologies. ▪ While it may be possible to develop responsive capabilities for this control through the use of AI and/or ML technologies, the criteria would be organization-specific to define.

Assessment Objectives

  1. NET-42.1_A01 system components to be isolated by boundary protection mechanisms are defined.
  2. NET-42.1_A02 boundary protection mechanisms are employed to isolate system components supporting missions and/or business functions.
  3. NET-42.1_A03 missions and/or business functions to be supported by system components isolated by boundary protection mechanisms are defined.
  4. NET-42.1_A04 physical isolation techniques are defined.
  5. NET-42.1_A05 logical isolation techniques are defined.
  6. NET-42.1_A06 physical isolation techniques and/or organization-defined logical isolation techniques are employed in organizational systems and system components.

Technology Recommendations

Micro/Small

  • Use VLANs or separate physical networks for sensitive systems

Small

  • VLAN segmentation for critical systems
  • Network isolation policy

Medium

  • Network segmentation with VLANs
  • Isolated segments for sensitive systems
  • Inter-VLAN firewall rules

Large

  • Enterprise network segmentation program
  • Microsegmentation for sensitive workloads
  • SDN-based isolation

Enterprise

  • Enterprise microsegmentation platform (e.g., Illumio, VMware NSX)
  • Zero-trust workload isolation
  • Automated policy enforcement

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