Control: 4.4 Ensure oslogin is enabled for a Project

Description

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

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.

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

Remediation

From Console

Login to GCP VM Console.
Select the instance and click Edit.
Navigate to Metadata section in the left panel.
Add a metadata entry where the key is enable-oslogin and the value is TRUE.
Click Save to apply the changes.
Ensure that no instance in the project overrides the project setting.
See more detail here

From Command Line

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

Usage

Run the control in your terminal:

powerpipe control run gcp_compliance.control.cis_v130_4_4

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run gcp_compliance.control.cis_v130_4_4 --share

SQL

This control uses a named query:

  with project_metadata as (
    select
      m.project,
      coalesce(
        (
          select lower(item ->> 'value')
          from jsonb_array_elements(m.common_instance_metadata -> 'items') as item
          where lower(item ->> 'key') = 'enable-oslogin'
          limit 1
        ), ''
      ) as project_oslogin
    from
      gcp_compute_project_metadata m
  ), instance_metadata as (
    select
      i.self_link,
      i.title,
      i.project,
      i.tags,
      i.location,
      i._ctx,
      coalesce(
        (
          select lower(item ->> 'value')
          from jsonb_array_elements(i.metadata -> 'items') as item
          where lower(item ->> 'key') = 'enable-oslogin'
          limit 1
        ), ''
      ) as instance_oslogin
    from
      gcp_compute_instance i
  )
select
  i.self_link as resource,
  case
    when pm.project_oslogin = '' then 'alarm'
    when pm.project_oslogin in ('false', 'n', 'no', '0') then 'alarm'
    when pm.project_oslogin in ('true', 'y', 'yes', '1')
        and i.instance_oslogin in ('false', 'n', 'no', '0') then 'alarm'
    else 'ok'
  end as status,
  case
    when pm.project_oslogin = '' then i.title || ' has OS login disabled at project level.'
    when pm.project_oslogin in ('false', 'n', 'no', '0') then i.title || ' has OS login disabled at project level.'
    when pm.project_oslogin in ('true', 'y', 'yes', '1') and i.instance_oslogin in ('false', 'n', 'no', '0') then i.title || ' OS login setting is disabled at instance level.'
    when pm.project_oslogin in ('true', 'y', 'yes', '1') and i.instance_oslogin = '' then i.title || ' inherits OS login enabled setting from project level.'
    else i.title || ' OS login enabled.'
  end as reason
  
  , i.location as location, i.project as project
from
  instance_metadata i
  left join project_metadata pm on pm.project = i.project;