Abnormally High AWS Instances Launched by User

Name:Abnormally High AWS Instances Launched by User
id:2a9b80d3-6340-4345-b5ad-290bf5d0dac4
version:4
date:2024-10-17
author:Bhavin Patel, Splunk
status:deprecated
type:Anomaly
Description:This search looks for AWS CloudTrail events where a user successfully launches an abnormally high number of instances. This search is deprecated and have been translated to use the latest Change Datamodel
Data_source:

search:`cloudtrail` eventName=RunInstances errorCode=success
| bucket span=10m _time
| stats count AS instances_launched by _time userName
| eventstats avg(instances_launched) as total_launched_avg, stdev(instances_launched) as total_launched_stdev
| eval threshold_value = 4
| eval isOutlier=if(instances_launched > total_launched_avg+(total_launched_stdev * threshold_value), 1, 0)
| search isOutlier=1 AND _time >= relative_time(now(), "-10m@m")
| eval num_standard_deviations_away = round(abs(instances_launched - total_launched_avg) / total_launched_stdev, 2)
| table _time, userName, instances_launched, num_standard_deviations_away, total_launched_avg, total_launched_stdev
| `abnormally_high_aws_instances_launched_by_user_filter`

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. The threshold value should be tuned to your environment.
known_false_positives:Many service accounts configured within an AWS infrastructure are known to exhibit this behavior. Please adjust the threshold values and filter out service accounts from the output. Always verify if this search alerted on a human user.
References:
drilldown_searches:
  :
tags:
  analytic_story:
    - 'AWS Cryptomining'
    - 'Suspicious AWS EC2 Activities'
  asset_type:AWS Instance
  confidence:50
  impact:50
  message:tbd
  mitre_attack_id:
    - 'T1078.004'
  observable:
    name:'userName'
    type:'User'
    - role:
      - 'Victim'
  product:
    - 'Splunk Enterprise'
    - 'Splunk Enterprise Security'
    - 'Splunk Cloud'
  required_fields:
    - '_time'
    - 'eventName'
    - 'errorCode'
    - 'userName'
  risk_score:25.0
  security_domain:network

tests:
  :
manual_test:None