ID | Technique | Tactic |
---|---|---|
T1537 | Transfer Data to Cloud Account | Exfiltration |
Detection: AWS EC2 Snapshot Shared Externally
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.
Search
1`cloudtrail` eventName=ModifySnapshotAttribute
2| rename requestParameters.createVolumePermission.add.items{}.userId as requested_account_id
3| search requested_account_id != NULL
4| eval match=if(requested_account_id==aws_account_id,"Match","No Match")
5| table _time user_arn src_ip requestParameters.attributeType requested_account_id aws_account_id match vendor_region user_agent userIdentity.principalId
6| where match = "No Match"
7| `aws_ec2_snapshot_shared_externally_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
AWS CloudTrail ModifySnapshotAttribute | AWS | 'aws:cloudtrail' |
'aws_cloudtrail' |
N/A |
Macros Used
Name | Value |
---|---|
cloudtrail | sourcetype=aws:cloudtrail |
aws_ec2_snapshot_shared_externally_filter | search * |
aws_ec2_snapshot_shared_externally_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Notable | Yes |
Rule Title | %name% |
Rule Description | %description% |
Notable Event Fields | user, dest |
Creates Risk Event | True |
Implementation
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
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
AWS EC2 snapshot from account $aws_account_id$ is shared with $requested_account_id$ by user $user_arn$ from $src_ip$ | 48 | 60 | 80 |
References
-
https://labs.nettitude.com/blog/how-to-exfiltrate-aws-ec2-data/
-
https://stratus-red-team.cloud/attack-techniques/AWS/aws.exfiltration.ec2-share-ebs-snapshot/
-
https://hackingthe.cloud/aws/enumeration/loot_public_ebs_snapshots/
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | aws_cloudtrail |
aws:cloudtrail |
Integration | ✅ Passing | Dataset | aws_cloudtrail |
aws:cloudtrail |
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: GitHub | Version: 4