4.4 Ensure Oslogin Is Enabled for a Project - instances

Information

Enabling OS login binds SSH certificates to IAM users and facilitates effective SSH certificate management.

Rationale:

Enabling osLogin ensures that SSH keys used to connect to instances are mapped with IAM users. Revoking access to IAM user will revoke all the SSH keys associated with that particular user. It facilitates centralized and automated SSH key pair management which is useful in handling cases like response to compromised SSH key pairs and/or revocation of external/third-party/Vendor users.

Impact:

Enabling OS Login on project disables metadata-based SSH key configurations on all instances from a project. Disabling OS Login restores SSH keys that you have configured in project or instance meta-data.

Solution

From Google Cloud Console

Go to the VM compute metadata page by visiting: https://console.cloud.google.com/compute/metadata.

Click Edit.

Add a metadata entry where the key is enable-oslogin and the value is TRUE.

Click Save to apply the changes.

For every instance that overrides the project setting, go to the VM Instances page at https://console.cloud.google.com/compute/instances.

Click the name of the instance on which you want to remove the metadata value.

At the top of the instance details page, click Edit to edit the instance settings.

Under Custom metadata, remove any entry with key enable-oslogin and the value is FALSE

At the bottom of the instance details page, click Save to apply your changes to the instance.

From Google Cloud CLI

Configure oslogin on the project:

gcloud compute project-info add-metadata --metadata enable-oslogin=TRUE

Remove instance metadata that overrides the project setting.

gcloud compute instances remove-metadata <INSTANCE_NAME> --keys=enable-oslogin

Optionally, you can enable two factor authentication for OS login. For more information, see: https://cloud.google.com/compute/docs/oslogin/setup-two-factor-authentication.

Default Value:

By default, parameter enable-oslogin is not set, which is equivalent to setting it to FALSE.

See Also

https://workbench.cisecurity.org/benchmarks/9562