: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 with previously unseen instance types. 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: 2020-02-07
  • Author: David Dorsey, Splunk
  • ID: 65541c80-03c7-4e05-83c8-1dcd57a2e1ad

Annotations

ATT&CK
Kill Chain Phase
  • Exploitation
NIST
  • ID.AM
CIS20
  • CIS 1
CVE
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`cloudtrail` eventName=RunInstances [search `cloudtrail` eventName=RunInstances errorCode=success 
| fillnull value="m1.small" requestParameters.instanceType 
| stats earliest(_time) as earliest latest(_time) as latest by requestParameters.instanceType 
| rename requestParameters.instanceType as instanceType 
| inputlookup append=t previously_seen_ec2_instance_types.csv 
| stats min(earliest) as earliest max(latest) as latest by instanceType 
| outputlookup previously_seen_ec2_instance_types.csv 
| eval newType=if(earliest >= relative_time(now(), "-70m@m"), 1, 0) 
| `security_content_ctime(earliest)` 
| `security_content_ctime(latest)` 
| where newType=1 
| rename instanceType as requestParameters.instanceType 
| table requestParameters.instanceType] 
| spath output=user userIdentity.arn 
| rename requestParameters.instanceType as instanceType, responseElements.instancesSet.items{}.instanceId as dest 
| table _time, user, dest, instanceType 
| `ec2_instance_started_with_previously_unseen_instance_type_filter`

Macros

The SPL above uses the following Macros:

:information_source: ec2_instance_started_with_previously_unseen_instance_type_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
  • requestParameters.instanceType

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 Instance Types" support search once to create a history of previously seen instance types.

Known False Positives

It is possible that an admin will create a new system using a new instance type never used before. Verify with the creator that they intended to create the system with the new instance type.

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