Restrict VPN Peer IPs

Trend Micro Cloud One™ – Conformity is a continuous assurance tool that provides peace of mind for your cloud infrastructure, delivering over 750 automated best practice checks.

Risk level: Medium (should be achieved)

Ensure that only trusted IPv4 addresses can be configured as VPN peer IPs within your Google Cloud organization. Each trusted IP address must be defined explicitly in the conformity rule settings, on the Trend Micro Cloud One™ – Conformity account console.

Security

By default, any IP address can be a VPN peer IP for a Virtual Private Cloud (VPC) network. By enforcing the "Restrict VPN Peer IPs" constraint policy, you can control the IP addresses that can be configured as VPN peer IPs within your Google Cloud organization in order to meet security and compliance requirements.


Audit

To determine if "Restrict VPN Peer IPs" constraint policy is enforced at the GCP organization level, perform the following operations:

Using GCP Console

01 Sign in to Google Cloud Management Console with the organizational unit credentials.

02 Click on the deployment selector from the top navigation bar, select ALL to list all the existing deployments, then choose the Google Cloud organization that you want to examine.

03 Navigate to Cloud Identity and Access Management (IAM) dashboard at https://console.cloud.google.com/iam-admin/iam.

04 In the navigation panel, select Organization Policies to access the complete list of the policies available for your GCP organization.

05 Click inside the Filter by policy name or ID filter box, select Name and Restrict VPN Peer IPs to return the "Restrict VPN Peer IPs" policy.

06 Click on the name of the organization policy returned at the previous step.

07 On the Policy details page, under Effective policy, check the Allowed configuration attribute value. If the Allowed attribute value is set to All, the "Restrict VPN Peer IPs" policy constraints are not enforced for the entire organization, therefore any IP address can be configured as VPN peer IP within your Google Cloud organization.

08 Repeat steps no. 2 – 7 for each organization available in your Google Cloud account.

Using GCP CLI

01 Run organizations list command (Windows/macOS/Linux) using custom query filters to list the ID of each organization available within your Google Cloud account:

gcloud organizations list
    --format="table(name)"

02 The command output should return the requested organization identifiers (IDs):

ID
112233441122
123412341234

03 Run resource-manager org-policies describe command (Windows/macOS/Linux) using the ID of the GCP organization that you want to examine as identifier parameter, to describe the enforcement configuration of the "Restrict VPN Peer IPs" policy (i.e. "compute.restrictVpnPeerIPs" constraint) available for the selected GCP organization:

gcloud alpha resource-manager org-policies describe
compute.restrictVpnPeerIPs
    --effective
    --organization=112233441122
    --format="value(listPolicy.allValues)"

04 The command request should return the requested configuration information:

ALLOW

If the resource-manager org-policies describe command output returns ALLOW, the "Restrict VPN Peer IPs" policy constraints are not enforced for the entire organization, therefore any IP address can be configured as VPN peer IP within your Google Cloud organization.

05 Repeat step no. 3 and 4 for each organization created in your Google Cloud account.

Remediation / Resolution

To ensure that only trusted IPv4 addresses can be configured as VPN peer IPs, enable and configure the "Restrict VPN Peer IPs" organization policy by performing the following operations:

Using GCP Console

01 Sign in to your Trend Micro Cloud One™ – Conformity account, access Restrict VPN Peer IPs conformity rule settings and note the list of allowed IPv4 addresses.

02 Sign in to Google Cloud Management Console with the organizational unit credentials.

03 Click on the deployment selector from the top navigation bar, select ALL to list all the existing deployments, then choose the Google Cloud organization that you want to reconfigure.

04 Navigate to Cloud Identity and Access Management (IAM) dashboard at https://console.cloud.google.com/iam-admin/iam.

05 In the navigation panel, select Organization Policies to access the list with the constraint policies available for your organization.

06 Click inside the Filter by policy name or ID filter box, select Name and Restrict VPN Peer IPs to return only the "Restrict VPN Peer IPs" policy.

07 Click on the name of the organization policy returned at the previous step.

08 On the Policy details page, click on the EDIT button from the dashboard top menu to edit the selected policy.

09 On the Edit policy configuration page, perform the following actions:

  1. Under Applies to, select Customize to choose the type of the policy to apply (i.e. customized policy).
  2. To override the inherited policies completely, select Replace under Policy enforcement.
  3. To use explicit values, select Custom from the Policy values dropdown list.
  4. For Policy type, select Allow to specify that the listed values will be the only allowed values, and all other values will be denied.
  5. In the Custom values section, use the configuration controls to specify the trusted, space-separated IPv4 addresses that can be configured as VPN peer IPs within your GCP organization, identified at step no. 1.
  6. (Optional) To set a recommendation for other users, click SET RECOMMENDATION, enter a string value into the Recommended value text box, and click SET to apply the recommendation. This string value will be displayed in the Google Cloud console to provide guidance to users about this organization policy. This is just a communication tool, and does not affect the policy configuration.
  7. Click SAVE to apply the changes and enforce the "Restrict VPN Peer IPs" organization policy.

10 If required, repeat steps no. 3 – 9 to enable the constraint policy for other organizations available in your Google Cloud account.

Using GCP CLI

01 Sign in to your Trend Micro Cloud One™ – Conformity account, access Restrict VPN Peer IPs conformity rule settings and note the list of allowed IPv4 addresses.

02 Define the "Restrict VPN Peer IPs" policy constraints and save the YAML policy document to a file named cc-allowed-vpn-peer-ips.yaml. Use the list of trusted IPv4 addresses that can be configured as VPN peer IPs, identified at step no. 1, to configure the allowed_values list (e.g. 10.10.10.5, 10.10.10.6):

constraint: constraints/compute.restrictVpnPeerIPs
listPolicy:
  allowed_values:
    10.10.10.5
    10.10.10.6

03 Run resource-manager org-policies set-policy command (Windows/macOS/Linux) using the ID of the Google Cloud Platform (GCP) organization that you want to reconfigure as identifier parameter, to enforce the "Restrict VPN Peer IPs" policy (i.e. "compute.restrictVpnPeerIPs" constraint), using the policy document defined at the previous step, for the selected organization:

gcloud beta resource-manager org-policies set-policy cc-allowed-vpn-peer-ips.yaml
    --organization=112233441122

04 The command request should return the enforced organization policy metadata:

constraint: constraints/compute.restrictVpnPeerIPs
etag: abcdabcdabcd
listPolicy:
  allowedValues:
  - 10.10.10.5 10.10.10.6
updateTime: '2020-09-15T10:00:00.000Z'

05 If required, repeat step no. 3 and 4 to enforce the constraint policy for other organizations created within your Google Cloud account.

References

Publication date May 10, 2021

Unlock the Remediation Steps


Gain free unlimited access
to our full Knowledge Base


Over 750 rules & best practices
for AWS and Azure

You are auditing:

Restrict VPN Peer IPs

Risk level: Medium