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NET-17: DNS & Content Filtering

NET 9 — Critical Protect

Mechanisms exist to force Internet-bound network traffic through a proxy device (e.g., Policy Enforcement Point (PEP)) for URL content filtering and DNS filtering to limit a user's ability to connect to dangerous or prohibited Internet sites.

Renumbered: Formerly NET-18 in SCF 2025.4.

Code reused: In SCF 2025.4 and earlier, NET-17 was Data Loss Prevention (DLP). That control is now DCH-40.

Control Question: Does the organization force Internet-bound network traffic through a proxy device (e.g., Policy Enforcement Point (PEP)) for URL content filtering and DNS filtering to limit a user's ability to connect to dangerous or prohibited Internet sites?

General (23)
Framework Mapping Values
CIS CSC 8.1 9.0 9.2 9.3 13.10
CIS CSC 8.1 IG1 9.2
CIS CSC 8.1 IG2 9.2 9.3
CIS CSC 8.1 IG3 9.2 9.3 13.10
GovRAMP SC-07(08)
GovRAMP Moderate SC-07(08)
GovRAMP High SC-07(08)
ISO 27002 2022 5.14 8.23
ISO 27017 2015 13.2.1
ISO 27018 2025 5.14 8.23
MPA Content Security Program 5.3.1 TS-2.8 TS-2.10
NIST 800-53 R4 SC-7(8) SC-18(3)
NIST 800-53 R5.2 SC-07(08) SC-18(03)
NIST 800-53B R5 (moderate) (source) SC-07(08)
NIST 800-53B R5 (high) (source) SC-07(08)
NIST 800-82 R3 SC-07(08) SC-18(03)
NIST 800-82 R3 MODERATE OT Overlay SC-07(08)
NIST 800-82 R3 HIGH OT Overlay SC-07(08)
NIST 800-171 R2 (source) 3.1.3
NIST 800-171 R3 (source) 03.14.06.c
NIST 800-171A R3 (source) A.03.14.06.c[02]
NIST CSF 2.0 (source) DE.CM-03
SWIFT CSF 2025 1.4
US (12)
Framework Mapping Values
USA Federal CMS MARS-E 2.0 SC-7(8)
USA Federal CISA CPG 2022 2.M
USA Federal DHS CISA TIC 3.0 3.PEP.DO.DNSIN 3.PEP.DO.PDSER 3.PEP.EM.CFILT 3.PEP.EM.LCTPR 3.PEP.EM.MLPRO 3.PEP.SE.MCFIL 3.PEP.WE.CFILT 3.PEP.WE.DCFIL 3.PEP.WE.DREPF 3.PEP.WE.DRESF 3.PEP.WE.MCFIL
USA Federal C2M2 2.1 ARCHITECTURE-2g ARCHITECTURE-5f
USA Federal CMMC 2.0 Level 2 ACL2.-3.1.3
USA Federal CJIS Security Policy 6.0 SC-7(8)
USA Federal FedRAMP R5 (moderate) SC-07(08)
USA Federal FedRAMP R5 (high) SC-07(08)
USA Federal IRS 1075 2021 SC-7(CE-8)
USA Federal TSA SDP 2021-02F III.D.1.b III.D.1.c III.D.1.e III.D.2.a
USA Federal TSA / DHS 1580/82-2022-01 III.D.1.b III.D.1.c III.D.1.e III.D.2.a
USA New York DFS 23 NYCRR500 2023 Amd 2 500.14(a)(2)
EMEA (10)
APAC (4)
Framework Mapping Values
APAC Australia ISM June 2026 ISM-0267 ISM-0649 ISM-0659 ISM-0958 ISM-0961 ISM-0963 ISM-1171 ISM-1234 ISM-1236 ISM-1237 ISM-1275 ISM-1287 ISM-1293 ISM-1502 ISM-1524 ISM-1965
APAC Malaysia RMiT 2025 A5-A4(c)
APAC New Zealand NZISM 3.9 9.3.6.C.01 14.3.6.C.01 14.3.6.C.02 14.3.6.C.03 14.3.10.C.01 14.3.10.C.02 14.3.10.C.03 14.3.10.C.04 14.3.11.C.01 14.3.11.C.02 14.3.12.C.01 20.3.9.C.01 20.3.10.C.01 20.3.11.C.01 20.3.11.C.02 21.3.7.C.01 21.3.7.C.02 21.3.14.C.01
APAC Singapore MAS TRM 2021 11.2.7
Americas (1)
Framework Mapping Values
Americas Canada ITSP-10-171 2025 03.14.06.C

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

Network Security (NET) domain capabilities are ad hoc and inconsistent. Capability criteria associated with this control may include: ▪ Policies, standards & procedures associated with NET domain capabilities provide limited coverage due to the depth and breadth of the existing documentation. ▪ Network security-related activities are decentralized (e.g., a localized/regionalized function) and uses non-standardized methods to implement secure, resilient and compliant practices.

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. ▪ SBC enforce Internet-bound network traffic routing through a proxy device for URL content filtering to limit a user's ability to connect to prohibited content. ▪ Content filtering blocks users from performing ad hoc file transfers through unapproved file transfer services (e.g., Box, Dropbox and Google Drive).

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 force Internet-bound network traffic through a proxy device (e.g., Policy Enforcement Point (PEP)) for URL content filtering and DNS filtering to limit a user's ability to connect to dangerous or prohibited Internet sites.

Level 4 — Quantitatively Controlled

Network Security (NET) capabilities, in addition to being standardized across the entity and centrally managed to ensure consistency across Technology Assets, Applications, Services and/or Data (TAASD), efforts are metrics driven to provide sufficient insight for decision makers to predict optimal performance, ensure continued operations and/or identify areas for improvement. Capability criteria associated with this control reasonably expect the following criteria to exist: ▪ Applicable SCR-CMM Level 3 (Well Defined) capabilities are implemented and operational. ▪ Metrics reporting includes quantitative analysis of Key Performance Indicators (KPIs). ▪ Metrics reporting includes quantitative analysis of Key Risk Indicators (KRIs). ▪ Scope of metrics, KPIs and KRIs covers organization-wide cybersecurity and data protection controls, including functions performed by third-parties. ▪ Organizational leadership maintains a formal process to objectively review and respond to metrics, KPIs and KRIs (e.g., monthly or quarterly review). ▪ Based on metrics analysis, process improvement recommendations are submitted for review and are handled in accordance with change control processes. ▪ Business and technical stakeholders are involved in reviewing and approving proposed changes to evolve capabilities.

Level 5 — Continuously Improving

Network Security (NET) capabilities, in addition to being standardized across the entity and centrally managed to ensure consistency across Technology Assets, Applications, Services and/or Data (TAASD), efforts are metrics driven to provide sufficient insight for decision makers to predict optimal performance, ensure continued operations and/or identify areas for improvement. Capability criteria associated with this control reasonably expect the following criteria to exist: ▪ Applicable SCR-CMM Level 3 (Well Defined) capabilities are implemented and operational. ▪ Based on predictive analysis, process improvements are implemented according to “continuous improvement” practices that affect process changes. ▪ Stakeholders make time-sensitive decisions to support operational efficiency, which may include automated remediation actions via Artificial Intelligence (AI) or Machine Learning (ML) technologies.

Assessment Objectives

  1. NET-17_A01 Internet-bound network traffic is routed through a proxy device or service for URL content filtering and DNS filtering to limit a user's ability to connect to dangerous or prohibited Internet sites.

Evidence Requirements

E-NET-01 Content / DNS Filtering

Documented evidence of the methods that content / DNS filtering is implemented to prevent Internet traffic from prohibited content and/or hostile web sites.

Network Security

Technology Recommendations

Micro/Small

  • Secure Baseline Configurations (SBC)

Small

  • Secure Baseline Configurations (SBC)

Medium

  • Secure Baseline Configurations (SBC)

Large

  • Secure Baseline Configurations (SBC)

Enterprise

  • Secure Baseline Configurations (SBC)

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