ID | Technique | Tactic |
---|---|---|
T1078.004 | Cloud Accounts | Defense Evasion |
Detection: EC2 Instance Modified With Previously Unseen User
DEPRECATED DETECTION
This detection has been marked as deprecated by the Splunk Threat Research team. This means that it will no longer be maintained or supported. If you have any questions or concerns, please reach out to us at research@splunk.com.
Description
This search looks for EC2 instances being modified by users who have not previously modified them. This search is deprecated and have been translated to use the latest Change Datamodel.
Search
1`cloudtrail` `ec2_modification_api_calls` [search `cloudtrail` `ec2_modification_api_calls` errorCode=success
2| stats earliest(_time) as firstTime latest(_time) as lastTime by userIdentity.arn
3| rename userIdentity.arn as arn
4| inputlookup append=t previously_seen_ec2_modifications_by_user
5| stats min(firstTime) as firstTime, max(lastTime) as lastTime by arn
6| outputlookup previously_seen_ec2_modifications_by_user
7| eval newUser=if(firstTime >= relative_time(now(), "-70m@m"), 1, 0)
8| where newUser=1
9| `security_content_ctime(firstTime)`
10| `security_content_ctime(lastTime)`
11| rename arn as userIdentity.arn
12| table userIdentity.arn]
13| spath output=dest responseElements.instancesSet.items{}.instanceId
14| spath output=user userIdentity.arn
15| table _time, user, dest
16| `ec2_instance_modified_with_previously_unseen_user_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
N/A | N/A | N/A | N/A | N/A |
Macros Used
Name | Value |
---|---|
cloudtrail | sourcetype=aws:cloudtrail |
ec2_instance_modified_with_previously_unseen_user_filter | search * |
ec2_instance_modified_with_previously_unseen_user_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 Risk Event | True |
Implementation
You must install the AWS App for Splunk (version 5.1.0 or later) and Splunk Add-on for AWS (version 4.4.0 or later), then configure your AWS CloudTrail inputs. This search works best when you run the "Previously Seen EC2 Launches By User" support search once to create a history of previously seen ARNs. To add or remove APIs that modify an EC2 instance, edit the macro ec2_modification_api_calls
.
Known False Positives
It's possible that a new user will start to modify EC2 instances when they haven't before for any number of reasons. Verify with the user that is modifying instances that this is the intended behavior.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
tbd | 25 | 50 | 50 |
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | Not Applicable | N/A | N/A | N/A |
Unit | ❌ Failing | N/A | N/A |
N/A |
Integration | ❌ Failing | N/A | N/A |
N/A |
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