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NET-20: Visibility of Encrypted Communications

NET 5 — Medium Detect

Mechanisms exist to configure the proxy to make encrypted communications traffic visible to monitoring tools and mechanisms.

Renumbered: Formerly NET-18.2 in SCF 2025.4.

Code reused: In SCF 2025.4 and earlier, NET-20 was Email Content Protections. That control is now NET-40.3.

Control Question: Does the organization configure the proxy to make encrypted communications traffic visible to monitoring tools and mechanisms?

General (5)
Framework Mapping Values
NIST 800-53 R5.2 SI-04(10)
NIST 800-53B R5 (high) (source) SI-04(10)
NIST 800-82 R3 SI-04(10)
NIST 800-82 R3 HIGH OT Overlay SI-04(10)
NIST 800-160 Vol2 R1 SI-04(10)
US (3)
Framework Mapping Values
USA Federal DHS CISA TIC 3.0 3.PEP.WE.BINSP
USA Federal FedRAMP R5 (high) SI-04(10)
USA Federal IRS 1075 2021 SI-4(CE-10)
APAC (3)
Framework Mapping Values
APAC Australia ISM June 2026 ISM-0263
APAC Malaysia RMiT 2025 10.21(d) A5-A4(b)
APAC New Zealand NZISM 3.9 14.3.8.C.01 14.3.9.C.01

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 configure the proxy to make encrypted communications traffic visible to monitoring tools and mechanisms.

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-20_A01 encrypted communications traffic to be made visible to system monitoring tools and mechanisms is defined.
  2. NET-20_A02 system monitoring tools and mechanisms to be provided access to encrypted communications traffic are defined.
  3. NET-20_A03 provisions are made so that encrypted communications traffic is visible to system monitoring tools and mechanisms.

Technology Recommendations

Micro/Small

  • Enable TLS inspection on proxy/firewall if supported

Small

  • TLS inspection on web proxy or NGFW

Medium

  • SSL/TLS inspection policy and implementation on SWG/NGFW

Large

  • Enterprise TLS inspection solution with privacy controls

Enterprise

  • Enterprise SSL/TLS inspection platform (e.g., Zscaler, BlueCoat)
  • Selective decryption policy
  • Privacy compliance for inspection

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