Elastic high stable kql

AWS EC2 AMI Shared with Another Account

Identifies an AWS Amazon Machine Image (AMI) being shared with another AWS account. Adversaries with access may share an AMI with an external AWS account as a means of data exfiltration. AMIs can contain secrets, bash histories, code artifacts, and other sensitive data that adversaries may abuse if shared with unauthorized accounts. AMIs can be made publicly available accidentally as well.

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Detection Logic

data_stream.dataset: "aws.cloudtrail" and event.provider: "ec2.amazonaws.com"
    and event.action: ModifyImageAttribute and event.outcome: success
    and aws.cloudtrail.request_parameters: *add=*
    and not aws.cloudtrail.user_identity.invoked_by: "assets.marketplace.amazonaws.com"
    and not user_agent.original: (*packer-plugin-amazon* or *Ansible*)

False Positives

⚠ AMI sharing is a common practice in AWS environments. Ensure that the sharing is authorized before taking action. AWS Marketplace subscriptions automatically result in assets.marketplace.amazonaws.com invoking ModifyImageAttribute to share the AMI with your account. This rule excludes Marketplace-invoked sharing by design. Other AWS services like workspaces.amazonaws.com and backup.amazonaws.com may invoke this action when users configure sharing through WorkSpaces or Backup plans. Review such service-invoked events to confirm they match legitimate and intended sharing configurations.

Field Validations

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