Control: 1.14 Ensure API Keys Are Restricted to Only APIs That Application Needs Access

Description

API Keys should only be used for services in cases where other authentication methods are unavailable. API keys are always at risk because they can be viewed publicly, such as from within a browser, or they can be accessed on a device where the key resides. It is recommended to restrict API keys to use (call) only APIs required by an application.

Security risks involved in using API-Keys are below:

API keys are simple encrypted strings
API keys do not identify the user or the application making the API request
API keys are typically accessible to clients, making it easy to discover and steal an API key

In light of these potential risks, Google recommends using the standard authentication flow instead of API-Keys. However, there are limited cases where API keys are more appropriate. For example, if there is a mobile application that needs to use the Google Cloud Translation API, but doesn't otherwise need a backend server, API keys are the simplest way to authenticate to that API.

In order to reduce attack surfaces by providing least privileges, API-Keys can be restricted to use (call) only APIs required by an application.

Remediation

From Console

Go to APIs & Services\Credentials using https://console.cloud.google.com/apis/credentials.
In the section API Keys, Click the API Key Name. The API Key properties display on a new page.
In the Key restrictions section go to API restrictions.
Click the Select API drop-down to choose an API.
Click Save.
Repeat steps 2,3,4,5 for every unrestricted API key.

Note: Do not set API restrictions to Google Cloud APIs, as this option allows access to all services offered by Google cloud.

From Google Cloud CLI

List all API keys.

gcloud services api-keys list

Note the UID of the key to add restrictions to.
Run the update command with the appropriate API target service or flags file with API target services and methods to add the required restrictions.

Command with appropriate API target service:

gcloud services api-keys update <UID> --api-target=service=<service>

Command with flags file:

gcloud services api-keys update <UID> --flags-file=<flags_file>.yaml

Content of flags file:

- --api-target:
service: "foo.service.com"
- --api-target:
service: "bar.service.com"
methods:
- "foomethod"
- "barmethod"

Note: Flags can be found by running:

gcloud services api-keys update --help

Note: Services can be found by running:

gcloud services list

or in this documentation https://cloud.google.com/sdk/gcloud/reference/services/api-keys/update

Default Value

By default, API restrictions are set to None.

Usage

Run the control in your terminal:

powerpipe control run gcp_compliance.control.cis_v400_1_14

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run gcp_compliance.control.cis_v400_1_14 --share

SQL

This control uses a named query:

  select
   'https://iam.googleapis.com/v1/projects/' || project || '/apikeys/' || name as resource,
  case
    when restrictions -> 'apiTargets' is null then 'alarm'
    else 'ok'
  end as status,
  case
    when restrictions -> 'apiTargets' is null then title || ' API key is not restricted to required APIs.'
    else title || ' API key is restricted to only required APIs.'
  end as reason
  , location as location, project as project
from
  gcp_apikeys_key;