LoFP / it is possible that an aws admin has legitimately shared a snapshot with an other account for a specific purpose. please check any recent change requests filed in your organization.

Techniques

• T1537

Sample rules

AWS Exfiltration via EC2 Snapshot

• source: splunk
• technicques:
  • T1537

Description

The following analytic detects a series of AWS API calls related to EC2 snapshots within a short time window, indicating potential exfiltration via EC2 Snapshot modifications. It leverages AWS CloudTrail logs to identify actions such as creating, describing, and modifying snapshot attributes. This activity is significant as it may indicate an attacker attempting to exfiltrate data by sharing EC2 snapshots externally. If confirmed malicious, the attacker could gain access to sensitive information stored in the snapshots, leading to data breaches and potential compliance violations.

Detection logic

`cloudtrail` eventName IN ("CreateSnapshot", "DescribeSnapshotAttribute", "ModifySnapshotAttribute", "DeleteSnapshot") src_ip !="guardduty.amazonaws.com" 
|  bin _time span=5m 
|  stats count dc(eventName) as distinct_api_calls values(eventName)  values(requestParameters.attributeType) as attributeType values(requestParameters.createVolumePermission.add.items{}.userId) as aws_account_id_added values(userAgent) as userAgent by _time userName src_ip aws_account_id 
| where distinct_api_calls >= 2 
| `aws_exfiltration_via_ec2_snapshot_filter`