New Private Repository Container Image detected in AWS ECR
Goal
Detect potential persistence mechanisms being deployed in the AWS Elastic Container Registry (ECR).
NOTE: Amazon ECR requires that users have permission to make calls to the ecr:GetAuthorizationToken
API through an IAM policy before they can authenticate to a registry and push or pull any images from any Amazon ECR repository.
Strategy
Detect when @evt.name:PutImage
is used against the ecr.amazonaws.com
API.
Triage & Response
- Check that
{{@responseElements.image.imageId.imageDigest}}
is a valid sha256 hash for the container image with a tag of {{@responseElements.image.imageId.imageTag}}
in the {{@responseElements.image.repositoryName}}
repository on AWS Account {{@userIdentity.accountId}}
. - If the hash is not valid for that container image, determine if the container image was placed there for a malicious purpose.