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Ensure firewall rule does not allow all traffic on all ports

### Overview

Category

Controls

Medium

Applies to

Google Cloud

Coverage

null controls, 1 queries

Asset types

1 covered

Overview

Overview

Allowing access from arbitrary IP addresses on all ports greatly increases the attack surface of your network. We recommend to allow traffic only from specific IP addresses and on specific ports by following a whitelist approach.

Remediation guidance

If the Firewall rule reported indeed needs to restrict all traffic, follow the instructions below:

  1. Login to GCP Console
  2. Go to 'VPC Network'
  3. Go to the 'Firewall'
  4. Click on the reported Firewall rule
  5. Click on 'EDIT'
  6. Modify Source IP ranges to specific IP
  7. Click on 'SAVE'

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.

Firewall rule does not allow all traffic on all ports

Connectors

Google Cloud

Covered asset types

Firewall

Expected check: eq []

{firewalls(where: {rules_SOME: {direction: "Inbound", destFromPort_LTE: 0, destToPort_GTE: 65535, OR: [{sources_INCLUDES: "cidr:0.0.0.0/0"}, {sources_INCLUDES: "cidr:::/0"}]}}) {...AssetFragment}}
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