ID | Technique | Tactic |
---|---|---|
T1537 | Transfer Data to Cloud Account | Exfiltration |
Detection: AWS Exfiltration via EC2 Snapshot
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.
Search
1`cloudtrail` eventName IN ("CreateSnapshot", "DescribeSnapshotAttribute", "ModifySnapshotAttribute", "DeleteSnapshot") src_ip !="guardduty.amazonaws.com"
2| bin _time span=5m
3| 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
4| where distinct_api_calls >= 2
5| `aws_exfiltration_via_ec2_snapshot_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
AWS CloudTrail CreateSnapshot | AWS | 'aws:cloudtrail' |
'aws_cloudtrail' |
AWS CloudTrail DeleteSnapshot | AWS | 'aws:cloudtrail' |
'aws_cloudtrail' |
AWS CloudTrail ModifySnapshotAttribute | AWS | 'aws:cloudtrail' |
'aws_cloudtrail' |
Macros Used
Name | Value |
---|---|
cloudtrail | sourcetype=aws:cloudtrail |
aws_exfiltration_via_ec2_snapshot_filter | search * |
aws_exfiltration_via_ec2_snapshot_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. We have intentionally removed guardduty.amazonaws.com
from src_ip to remove false positives caused by guard duty. We recommend you adjust the time window as per your environment.
Known False Positives
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.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
Potential AWS EC2 Exfiltration detected on account id - $aws_account_id$ by user $userName$ from src_ip $src_ip$ | 64 | 80 | 80 |
References
-
https://labs.nettitude.com/blog/how-to-exfiltrate-aws-ec2-data/
-
https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_ModifySnapshotAttribute.html
-
https://bleemb.medium.com/data-exfiltration-with-native-aws-s3-features-c94ae4d13436
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: 3