Try in Splunk Security Cloud

Description

The following analytic detects when an EC2 snapshot is shared with an external AWS account by analyzing AWS CloudTrail events. This detection method leverages CloudTrail logs to identify modifications in snapshot permissions, specifically when the snapshot is shared outside the originating AWS account. This activity is significant as it may indicate an attempt to exfiltrate sensitive data stored in the snapshot. If confirmed malicious, an attacker could gain unauthorized access to the snapshot's data, potentially leading to data breaches or further exploitation of the compromised information.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-07
  • Author: Bhavin Patel, Splunk
  • ID: 2a9b80d3-6340-4345-b5ad-290bf3d222c4

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1537 Transfer Data to Cloud Account Exfiltration
Kill Chain Phase
  • Actions On Objectives
NIST
  • DE.CM
CIS20
  • CIS 10
CVE
1
2
3
4
5
6
7
`cloudtrail` eventName=ModifySnapshotAttribute 
| rename requestParameters.createVolumePermission.add.items{}.userId as requested_account_id 
| search requested_account_id != NULL 
| eval match=if(requested_account_id==aws_account_id,"Match","No Match") 
| table _time user_arn src_ip requestParameters.attributeType requested_account_id aws_account_id match vendor_region user_agent userIdentity.principalId 
| where match = "No Match" 
| `aws_ec2_snapshot_shared_externally_filter` 

Macros

The SPL above uses the following Macros:

:information_source: aws_ec2_snapshot_shared_externally_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • eventName
  • user_arn
  • src_ip
  • requestParameters.attributeType
  • aws_account_id
  • vendor_region
  • user_agent
  • userIdentity.principalId

How To Implement

You must install splunk AWS add on and Splunk App for AWS. This search works with AWS CloudTrail logs.

Known False Positives

It is possible that an AWS admin has legitimately shared a snapshot with others for a specific purpose.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
48.0 60 80 AWS EC2 snapshot from account $aws_account_id$ is shared with $requested_account_id$ by user $user_arn$ from $src_ip$

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 4