NET-06: Network Segmentation (macrosegementation)

There is no evidence of a capability to ensure network architecture utilizes network segmentation to isolate Technology Assets, Applications and/or Services (TAAS) to protect from other network resources.

Network Security (NET) efforts are ad hoc and inconsistent. CMM Level 1 control maturity would reasonably expect all, or at least most, the following criteria to exist:

• IT personnel use an informal process to design, build and maintain secure networks for test, development, staging and production environments, including the implementation of appropriate cybersecurity and data protection controls.
• 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 monitoring is primarily reactive in nature.

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).
• Administrative processes require De-Militarized Zone (DMZ) network segments to separate untrusted networks from trusted networks.
• IT/cybersecurity architects maintain a segmented development network to ensure a secure development environment.

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).

Network Security (NET) efforts are metrics driven and provide sufficient management insight (based on a quantitative understanding of process capabilities) to predict optimal performance, ensure continued operations and identify areas for improvement. In addition to CMM Level 3 criteria, CMM Level 4 control maturity would reasonably expect all, or at least most, the following criteria to exist:

• 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.
• Both business and technical stakeholders are involved in reviewing and approving proposed changes.

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 ensure network architecture utilizes network segmentation to isolate Technology Assets, Applications and/or Services (TAAS) to protect from other network resources.