Cloud Security Maturity Model 2.0
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NET-04.2: Implement initial minimum viable network designs
NET-04.2: Minimum viable networks only implement the minimum network resources required for an application to function, with strict security group and route table rules. This minimizes opportunities for attackers to move laterally and reduces the blast radius of network attacks. While it is not possible to completely evaluate this with automation, checks can look for key indications that these concepts are in use. Options include looking for tightly scoped route tables and security groups, use of a transit gateway, and the existence of service endpoints.
  • Control automation: Either
  • AWS control specification: * Check route tables for rules that trust > /24 subnets
  • VPCs should not have more than 20 subnets
  • If there are more than four peered VPCs in the org, there should be at least one Transit Gateway
  • Azure control specification: none
  • GCP control specification: none
  • Third-party (CSPM/CNAPP) control specification: none
Not Applicable - Not applicable
Level 1: Initial - Initial. Manually managing policies/procedures, mostly through console. Architectures tend to resemble traditional infrastructure (e.g., low use of serverless and high reliance on network security controls). IAM mostly ad hoc with little-to-no federation.
Level 2: Repeatable - Repeatable. Policy-/checklist-based and relies more on manual or simple tooling. High variability between projects; not coordinated across deployments. Initial use of infrastructure as code (Terraform/CloudFormation), but security not consistently engaged in design/review. Federation on some accounts, but limited use of MFA due to difficulties supporting teams (especially on the command line).
Level 3: Defined - Defined. Policies and central coordination in place. Some initial security automation still executed manually. Some third-party tooling (orchestration with other tools), Federation on most accounts with widespread MFA, but still gaps on consistency. Security starting to review and promote use of CloudFormation/Terraform. CSPM/CNAPP (CSP or third party) in use.
Level 4: Capable - Capable. Strong centralized security management with consistent enforcement. Automation and guardrails across multiple deployments. Expanding library. Big shift from manual management and execution to running security operations with centralized platforms with centralized management and reporting. Consistent use of federation and MFA, with some gaps supporting toolchains.
Level 5: Efficient - Efficient. All major activities centrally managed, covering all of the CSMM domains. Integrated into infrastructure-as-code (IaC) environment. Built into the stack with provisioning automation. Federation and MFA working consistently across toolchains (e.g., command-line support).

Description
  • Control automation: Either
  • AWS control specification: * Check route tables for rules that trust > /24 subnets
  • VPCs should not have more than 20 subnets
  • If there are more than four peered VPCs in the org, there should be at least one Transit Gateway
  • Azure control specification: none
  • GCP control specification: none
  • Third-party (CSPM/CNAPP) control specification: none