Google CloudOverview
**Description: **
In order to prevent use of legacy networks, a project should not have a legacy network configured.
Rationale
Legacy networks have a single network IPv4 prefix range and a single gateway IP address for the whole network. The network is global in scope and spans all cloud regions. You cannot create subnetworks in a legacy network or switch from legacy to auto or custom subnet networks. Legacy networks can thus have an impact for high network traffic projects and subject to the single point of contention or failure.
Remediation guidance
For each Google Cloud Platform project,
- Follow the documentation and create a non-legacy network suitable for your requirements.
- Follow the documentation and delete the networks in the
legacymode.
Default Value
By default, networks are not created in the legacy mode.
References
- https://cloud.google.com/compute/docs/networking#creating_a_legacy_network
- https://cloud.google.com/compute/docs/networking#legacy_non-subnet_network
Google Cloud Console (Asset-Level)
- Open the affected project/resource from the finding details in Google Cloud Console.
- Navigate to the resource security/configuration settings.
- Apply the control-specific secure configuration.
- Save and re-run the check.
Multiple Remediation Paths
Google Cloud
SERVICE-WIDE (RECOMMENDED when many resources are affected): Enforce Organization Policies at org/folder level so new resources inherit secure defaults.
gcloud org-policies set-policy policy.yaml
ASSET-LEVEL: Use the product-specific remediation steps above for only the impacted project/resources.
PREVENTIVE: Use org policy constraints/custom constraints and enforce checks in deployment pipelines.
References for Service-Wide Patterns
- GCP Organization Policy overview: https://cloud.google.com/resource-manager/docs/organization-policy/overview
- GCP Organization policy constraints catalog: https://cloud.google.com/resource-manager/docs/organization-policy/org-policy-constraints
- gcloud org-policies: https://cloud.google.com/sdk/gcloud/reference/org-policies
Operational Rollout Workflow
Use this sequence to reduce risk and avoid repeated drift.
1. Contain at Service-Wide Scope First (Recommended)
- Google Cloud: apply organization policy constraints at org/folder scope.
gcloud org-policies set-policy policy.yaml
2. Remediate Existing Affected Assets
- Execute the control-specific Console/CLI steps documented above for each flagged resource.
- Prioritize internet-exposed and production assets first.
3. Validate and Prevent Recurrence
- Re-scan after each remediation batch.
- Track exceptions with owner and expiry date.
- Add preventive checks in IaC/CI pipelines.
Query logic
These are the stored checks tied to this control.
Legacy networks do not exist for a project
Connectors
Covered asset types
Expected check: eq []
vpcs(where:{IPv4Range_NOT:"" gatewayIPv4_NOT:""}){...AssetFragment}
