:no_entry: THIS IS A DEPRECATED DETECTION

This detection has been marked deprecated by the Splunk Threat Research team. This means that it will no longer be maintained or supported.

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Description

This search looks for EC2 instances being created by users who have not created them before. This search is deprecated and have been translated to use the latest Change Datamodel.

  • Type: Anomaly

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

  • Last Updated: 2020-07-21
  • Author: David Dorsey, Splunk
  • ID: 22773e84-bac0-4595-b086-20d3f735b4f1

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1078.004 Cloud Accounts Defense Evasion, Persistence, Privilege Escalation, Initial Access
Kill Chain Phase
  • Exploitation
  • Installation
  • Delivery
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`cloudtrail` eventName=RunInstances [search `cloudtrail` eventName=RunInstances errorCode=success 
| stats earliest(_time) as firstTime latest(_time) as lastTime by userIdentity.arn 
| rename userIdentity.arn as arn 
| inputlookup append=t previously_seen_ec2_launches_by_user.csv 
| stats min(firstTime) as firstTime, max(lastTime) as lastTime by arn 
| outputlookup previously_seen_ec2_launches_by_user.csv 
| eval newUser=if(firstTime >= relative_time(now(), "-70m@m"), 1, 0) 
| where newUser=1 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| rename arn as userIdentity.arn 
| table userIdentity.arn] 
| rename requestParameters.instanceType as instanceType, responseElements.instancesSet.items{}.instanceId as dest, userIdentity.arn as user 
| table _time, user, dest, instanceType 
| `ec2_instance_started_with_previously_unseen_user_filter`

Macros

The SPL above uses the following Macros:

:information_source: ec2_instance_started_with_previously_unseen_user_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
  • errorCode
  • userIdentity.arn

How To Implement

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.

Known False Positives

It's possible that a user will start to create EC2 instances when they haven't before for any number of reasons. Verify with the user that is launching instances that this is the intended behavior.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 tbd

: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: 2