Lateral Movement: Modified Boot Disk Attached to Instance

This document describes a threat finding type in Security Command Center. Threat findings are generated by threat detectors when they detect a potential threat in your cloud resources. For a full list of available threat findings, see Threat findings index.

Finding description

Audit logs are examined to detect suspicious disk movements among Compute Engine instance resources. A potentially modified boot disk has been attached to your Compute Engine.

Step 1: Review finding details

  1. Open the Lateral Movement: Modify Boot Disk Attaching to Instance finding, as detailed in Reviewing findings. The details panel for the finding opens to the Summary tab.

  2. On the Summary tab, note the values of following fields.

    Under What was detected:

    • Principal email: the service account that performed the action
    • Service name: the API name of the Google Cloud service that was accessed by the service account
    • Method name: the method that was called

Step 2: Research attack and response methods

  1. Use service account tools, like Activity Analyzer, to investigate the activity of the associated service account.
  2. Contact the owner of the service account in the Principal email field. Confirm whether the legitimate owner conducted the action.

Step 3: Implement your response

The following response plan might be appropriate for this finding, but might also impact operations. Carefully evaluate the information you gather in your investigation to determine the best way to resolve findings.

  • Contact the owner of the project where the action was taken.
  • Consider using Secure Boot for your Compute Engine VM instances.
  • Consider deleting the potentially compromised service account and rotate and delete all service account access keys for the potentially compromised project. After deletion, applications that use the service account for authentication lose access. Before proceeding, your security team should identify all impacted applications and work with application owners to ensure business continuity.
  • Work with your security team to identify unfamiliar resources, including Compute Engine instances, snapshots, service accounts, and IAM users. Delete resources not created with authorized accounts.
  • Respond to any notifications from Google Cloud Support.

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