New Private Repository Container Image detected in AWS ECR

cloudtrail

Classification:

attack

Tactic:

TA0003-persistence

Technique:

T1525-implant-internal-image

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

  1. 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}}.
  2. If the hash is not valid for that container image, determine if the container image was placed there for a malicious purpose.