AWS EBS Snapshot possible exfiltration

cloudtrail

Classification:

attack

Tactic:

TA0010-exfiltration

Technique:

T1537-transfer-data-to-cloud-account

Goal

Detect the possible exfiltration of an EBS snapshot.

Strategy

This rule allows you to monitor CloudTrail and detect the following API calls within a 15 minute time window:

An attacker can create a EBS snapshot from the EBS volume and modify the permissions of the snapshot to allow it to be shared publicly or with another AWS account. Using an attacker-controlled account, a new EBS volume can be created from the snapshot and attached to an EC2 instance for analysis.

Triage and response

  1. Determine if {{@userIdentity.arn}} should have made the API calls.
  2. If the API call was not made by the user:
  • Rotate user credentials.
  • Determine what other API calls were made by the user.
  • Remove any snapshot attributes generated by the user with the aws-cli command modify-snapshot-attribute.
  • Begin your organization’s incident response process and investigate.
  1. If the API calls were made by the user:
  • Determine if the user should be performing these API calls.
  • If No, see if other API calls were made by the user and determine if they warrant further investigation.

Changelog

10 October 2022 - Updated query and severity.