AWSOverview
With IMDSv2, every request is now protected by session authentication. A session begins and ends a series of requests that software running on an EC2 instance uses to access the locally-stored EC2 instance metadata and credentials. The software starts a session with a simple HTTP PUT request to IMDSv2.
You can read more about it at in this AWS Blog post: Add defense in depth against open firewalls, reverse proxies, and SSRF vulnerabilities with enhancements to the EC2 Instance Metadata Service
Remediation guidance
AWS remediation
Console
- Open Launch Templates.
- Create a new version.
- Set metadata options: HttpTokens required.
- Set new version as default.
AWS CLI
aws ec2 create-launch-template-version \
--launch-template-id <lt-id> \
--source-version <current-version> \
--launch-template-data '{"MetadataOptions":{"HttpTokens":"required"}}'
aws ec2 modify-launch-template --launch-template-id <lt-id> --default-version <new-version-number>
References
- https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configuring-instance-metadata-service.html
- https://docs.aws.amazon.com/cli/latest/reference/ec2/create-launch-template-version.html
Service-wide remediation
Recommended when many resources are affected: fix the platform baseline first so new resources inherit the secure setting, then remediate the existing flagged resources in batches.
AWS
Use AWS Organizations guardrails, AWS Config rules or conformance packs where they fit, approved account baselines, and IaC modules so new resources inherit the secure setting.
Operational rollout
- Fix the baseline first at the account, subscription, project, cluster, or tenant scope that owns this control.
- Remediate the currently affected resources in batches, starting with internet-exposed and production assets.
- Re-scan and track approved exceptions with an owner and expiry date.
Query logic
These are the stored checks tied to this control.
Retrieve AWS Launch Templates without IMDSv2 required
Connectors
Covered asset types
Expected check: eq []
{
launchTemplateVersions(
where: { NOT: { metadataOptionHTTPTokens: "required" } }
) {...AssetFragment}
}
