Control: 6.7 Ensure that the EC2 Metadata Service only allows IMDSv2

Description

When enabling the Metadata Service on AWS EC2 instances, users have the option of using either Instance Metadata Service Version 1 (IMDSv1; a request/response method) or Instance Metadata Service Version 2 (IMDSv2; a session-oriented method).

Remediation

From Console:

Sign in to the AWS Management Console and navigate to the EC2 dashboard at https://console.aws.amazon.com/ec2/.
In the left navigation panel, under the INSTANCES section, choose Instances.
Select the EC2 instance that you want to examine.
Choose Actions > Instance Settings > Modify instance metadata options.
Set Instance metadata service to Enable.
Set IMDSv2 to Required.
Repeat steps 1-6 to perform the remediation process for other EC2 instances in all applicable AWS region(s).

From Command Line:

Run the describe-instances command, applying the appropriate filters to list the IDs of all existing EC2 instances currently available in the selected region:

aws ec2 describe-instances --region <region-name> --output table --query "Reservations[*].Instances[*].InstanceId"

The command output should return a table with the requested instance IDs.
Run the modify-instance-metadata-options command with an instance ID obtained from the previous step to update the Instance Metadata Version:

aws ec2 modify-instance-metadata-options --instance-id <instance-id> --http-tokens required --region <region-name>

Repeat steps 1-3 to perform the remediation process for other EC2 instances in the same AWS region.
Change the region by updating --region and repeat the process for other regions.

Default Value:

By default, new EC2 instances support both IMDSv1 and IMDSv2. IMDSv1 (less secure) remains enabled unless explicitly restricted, so IMDSv2 must be manually required.

Usage

Run the control in your terminal:

powerpipe control run aws_compliance.control.cis_v600_6_7

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run aws_compliance.control.cis_v600_6_7 --share

SQL

This control uses a named query:

select
  arn as resource,
  case
    when metadata_options ->> 'HttpTokens' = 'required' and metadata_options ->> 'State' = 'applied' then 'ok'
    else 'alarm'
  end as status,
  case
    when metadata_options ->> 'HttpTokens' = 'required' and metadata_options ->> 'State' = 'applied' then title || ' configured to use Instance Metadata Service Version 2 (IMDSv2).'
    else title || ' not configured to use Instance Metadata Service Version 2 (IMDSv2).'
  end as reason
  
  , region, account_id
from
  aws_ec2_instance;