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