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NET-20: Email Content Protections

NET 10 — Critical Protect

Mechanisms exist to implement an email filtering security service to detect malicious attachments in emails and prevent users from accessing them.

Control Question: Does the organization implement an email filtering security service to detect malicious attachments in emails and prevent users from accessing them?

General (2)
Framework Mapping Values
SCF CORE ESP Level 2 Critical Infrastructure NET-20
SCF CORE ESP Level 3 Advanced Threats NET-20
US (1)
Framework Mapping Values
US DHS CISA TIC 3.0 3.PEP.EM.E3AEP 3.PEP.EM.MFPRO

Capability Maturity Model

Level 0 — Not Performed

There is no evidence of a capability to implement an email filtering security service to detect malicious attachments in emails and prevent users from accessing them.

Level 1 — Performed Informally

C|P-CMM1 is N/A, since a structured process is required to implement an email filtering security service to detect malicious attachments in emails and prevent users from accessing them.

Level 2 — Planned & Tracked

Network Security (NET) efforts are requirements-driven and governed at a local/regional level, but are not consistent across the organization. CMM Level 2 control maturity would reasonably expect all, or at least most, the following criteria to exist:

  • Network security management is decentralized (e.g., a localized/regionalized function) and uses non-standardized methods to implement secure, resilient and compliant practices.
  • IT/cybersecurity personnel identify cybersecurity and data protection controls that are appropriate to address applicable statutory, regulatory and contractual requirements for network security management.
  • IT personnel define secure networking practices to protect the confidentiality, integrity, availability and safety of the organization's technology assets, data and network(s).
  • Administrative processes and technologies focus on protecting High Value Assets (HVAs), including environments where sensitive/regulated data is stored, transmitted and processed.
  • Administrative processes are used to configure boundary devices (e.g., firewalls, routers, etc.) to deny network traffic by default and allow network traffic by exception (e.g., deny all, permit by exception).
  • Network segmentation exists to implement separate network addresses (e.g., different subnets) to connect systems in different security domains (e.g., sensitive/regulated data environments).
  • Technologies are configured to force Internet-bound network traffic through a proxy device for URL content filtering to limit a user's ability to connect to prohibited content.
Level 3 — Well Defined

Network Security (NET) efforts are standardized across the organization and centrally managed, where technically feasible, to ensure consistency. CMM Level 3 control maturity would reasonably expect all, or at least most, the following criteria to exist:

  • A Technology Infrastructure team, or similar function, defines centrally-managed network security controls for implementation across the enterprise.
  • Secure engineering principles are used to design and implement network security controls (e.g., industry-recognized secure practices) to enforce the concepts of least privilege and least functionality at the network level.
  • IT/cybersecurity architects work with the Technology Infrastructure team to implement a “layered defense” network architecture that provides a defense-in-depth approach for redundancy and risk reduction for network-based security controls, including wired and wireless networking.
  • Administrative processes and technologies configure boundary devices (e.g., firewalls, routers, etc.) to deny network traffic by default and allow network traffic by exception (e.g., deny all, permit by exception).
  • Technologies automate the Access Control Lists (ACLs) and similar rulesets review process to identify security issues and/ or misconfigurations.
  • Network segmentation exists to implement separate network addresses (e.g., different subnets) to connect systems in different security domains (e.g., sensitive/regulated data environments).
Level 4 — Quantitatively Controlled

See C|P-CMM3. There are no defined C|P-CMM4 criteria, since it is reasonable to assume a quantitatively-controlled process is not necessary to implement an email filtering security service to detect malicious attachments in emails and prevent users from accessing them.

Level 5 — Continuously Improving

See C|P-CMM4. There are no defined C|P-CMM5 criteria, since it is reasonable to assume a continuously-improving process is not necessary to implement an email filtering security service to detect malicious attachments in emails and prevent users from accessing them.

Assessment Objectives

  1. NET-20_A01 an email filtering security service is implemented.
  2. NET-20_A02 email filtering security services are configured to detect malicious attachments in emails and prevent users from accessing them.
  3. NET-20_A03 email filtering security services are configured to prevent users from accessing malicious email attachments.

Technology Recommendations

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