LoFP LoFP / access removal may be a part of normal operations and should be verified before taking action.

Techniques

Sample rules

AWS EC2 EBS Snapshot Access Removed

Description

Identifies the removal of access permissions from a shared AWS EC2 EBS snapshot. EBS snapshots are essential for data retention and disaster recovery. Adversaries may revoke or modify snapshot permissions to prevent legitimate users from accessing backups, thereby obstructing recovery efforts after data loss or destructive actions. This tactic can also be used to evade detection or maintain exclusive access to critical backups, ultimately increasing the impact of an attack and complicating incident response.

Detection logic

from logs-aws.cloudtrail-* metadata _id, _version, _index
| where event.provider == "ec2.amazonaws.com" and event.action == "ModifySnapshotAttribute" and event.outcome == "success"
| dissect aws.cloudtrail.request_parameters "{%{?snapshotId}=%{snapshotId},%{?attributeType}=%{attributeType},%{?createVolumePermission}={%{operationType}={%{?items}=[{%{?userId}=%{userId}}]}}}"
| where operationType == "remove"
| keep @timestamp, aws.cloudtrail.user_identity.arn, cloud.account.id, event.action, snapshotId, attributeType, operationType, userId, source.address