Control: 1.10 Ensure KMS Encryption Keys Are Rotated Within a Period of 90 Days

Description

Google Cloud Key Management Service stores cryptographic keys in a hierarchical structure designed for useful and elegant access control management.

The format for the rotation schedule depends on the client library that is used. For the gcloud command-line tool, the next rotation time must be in ISO or RFC3339 format, and the rotation period must be in the form INTEGER[UNIT], where units can be one of seconds (s), minutes (m), hours (h) or days (d).

Set a key rotation period and starting time. A key can be created with a specified rotation period, which is the time between when new key versions are generated automatically. A key can also be created with a specified next rotation time. A key is a named object representing a cryptographic key used for a specific purpose. The key material, the actual bits used for encryption, can change over time as new key versions are created.

A key is used to protect some corpus of data. A collection of files could be encrypted with the same key and people with decrypt permissions on that key would be able to decrypt those files. Therefore, it's necessary to make sure the rotation period is set to a specific time.

Remediation

From Google Cloud Console

Go to Cryptographic Keys by visiting: https://console.cloud.google.com/security/kms.
Click on the specific key ring.
From the list of keys, choose the specific key and Click on Right side pop up the blade (3 dots).
Click on Edit rotation period.
On the pop-up window, Select a new rotation period in days which should be less than 90 and then choose Starting on date (date from which the rotation period begins).

From Google Cloud CLI

Update and schedule rotation by ROTATION_PERIOD and NEXT_ROTATION_TIME for each key:

gcloud kms keys update new --keyring=KEY_RING --location=LOCATION --next-rotation-time=NEXT_ROTATION_TIME --rotation-period=ROTATION_PERIOD

Default Value

By default, KMS encryption keys are rotated every 90 days.

Usage

Run the control in your terminal:

powerpipe control run gcp_compliance.control.cis_v400_1_10

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run gcp_compliance.control.cis_v400_1_10 --share

SQL

This control uses a named query:

select
  self_link as resource,
  case
    when "primary" ->> 'state' = 'DESTROYED' then 'skip'
    when "primary" ->> 'state' = 'DESTROY_SCHEDULED' then 'skip'
    when "primary" ->> 'state' = 'DISABLED' then 'skip'
    when split_part(rotation_period, 's', 1) :: int <= 7776000 then 'ok'
    else 'alarm'
  end as status,
  case
    when "primary" ->> 'state' = 'DESTROYED' then title || ' is destroyed.'
    when "primary" ->> 'state' = 'DESTROY_SCHEDULED' then title || ' is scheduled for deletion.'
    when "primary" ->> 'state' = 'DISABLED' then title || ' is disabled.'
    when rotation_period is null then title || ' in ' || key_ring_name || ' requires manual rotation.'
    else key_ring_name || ' ' || title || ' rotation period set for ' || (split_part(rotation_period, 's', 1) :: int)/86400 || ' day(s).'
  end as reason
  
  , location as location, project as project
from
  gcp_kms_key;