1.5 Ensure That Service Account Has No Admin Privileges

Information

A service account is a special Google account that belongs to an application or a VM, instead of to an individual end-user. The application uses the service account to call the service's Google API so that users aren't directly involved. It's recommended not to use admin access for ServiceAccount.

Rationale:

Service accounts represent service-level security of the Resources (application or a VM) which can be determined by the roles assigned to it. Enrolling ServiceAccount with Admin rights gives full access to an assigned application or a VM. A ServiceAccount Access holder can perform critical actions like delete, update change settings, etc. without user intervention. For this reason, it's recommended that service accounts not have Admin rights.

Impact:

Removing *Admin or *admin or Editor or Owner role assignments from service accounts may break functionality that uses impacted service accounts. Required role(s) should be assigned to impacted service accounts in order to restore broken functionalities.

Solution

From Google Cloud Console

Go to IAM & admin/IAM using https://console.cloud.google.com/iam-admin/iam

Go to the Members

Identify User-Managed user created service account with roles containing *Admin or *admin or role matching Editor or role matching Owner

Click the Delete bin icon to remove the role from the member (service account in this case)

From Google Cloud CLI

gcloud projects get-iam-policy PROJECT_ID --format json > iam.json

Using a text editor, Remove Role which contains roles/*Admin or roles/*admin or matched roles/editor or matches 'roles/owner'. Add a role to the bindings array that defines the group members and the role for those members.

For example, to grant the role roles/appengine.appViewer to the ServiceAccount which is roles/editor, you would change the example shown below as follows:

{
"bindings": [
{
"members": [
"serviceAccount:[email protected]",
],
"role": "roles/appengine.appViewer"
},
{
"members": [
"user:[email protected]"
],
"role": "roles/owner"
},
{
"members": [
"serviceAccount:[email protected]",
"serviceAccount:[email protected]"
],
"role": "roles/editor"
}
],
"etag": "BwUjMhCsNvY="
}

Update the project's IAM policy:
gcloud projects set-iam-policy PROJECT_ID iam.json

Default Value:

User Managed (and not user-created) default service accounts have the Editor (roles/editor) role assigned to them to support GCP services they offer.

By default, there are no roles assigned to User Managed User created service accounts.

See Also

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