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Description

This search looks for AWS CloudTrail events wherein a console login event by a user was recorded within the last hour, then compares the event to a lookup file of previously seen users (by ARN values) who have logged into the console. The alert is fired if the user has logged into the console for the first time within the last hour

  • Type: Hunting
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Authentication
  • Last Updated: 2022-08-25
  • Author: Bhavin Patel, Eric McGinnis Splunk
  • ID: 9f31aa8e-e37c-46bc-bce1-8b3be646d026

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1586 Compromise Accounts Resource Development
T1586.003 Cloud Accounts Resource Development
T1535 Unused/Unsupported Cloud Regions Defense Evasion
Kill Chain Phase
  • Actions on Objectives
NIST
  • DE.DP
  • DE.AE
CIS20
  • CIS 16
CVE 


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| tstats earliest(_time) as firstTime latest(_time) as lastTime from datamodel=Authentication where Authentication.signature=ConsoleLogin by Authentication.user Authentication.src 
| iplocation Authentication.src 
| `drop_dm_object_name(Authentication)` 
| rename Region as justSeenRegion 
| table firstTime lastTime user justSeenRegion 
| join user type=outer [
| inputlookup previously_seen_users_console_logins 
| rename Region as previouslySeenRegion 
| stats min(firstTime) AS earliestseen by user previouslySeenRegion 
| fields earliestseen user previouslySeenRegion] 
| eval userRegion=if(firstTime >= relative_time(now(), "-24h@h"), "New Region","Previously Seen Region") 
| where userRegion= "New Region" 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| table firstTime lastTime user previouslySeenRegion justSeenRegion userRegion 
| `detect_aws_console_login_by_user_from_new_region_filter`

Macros

The SPL above uses the following Macros:

:information_source: detect_aws_console_login_by_user_from_new_region_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Lookups

The SPL above uses the following Lookups:

Required fields

List of fields required to use this analytic.

  • _time
  • Authentication.signature
  • Authentication.user
  • Authentication.src

How To Implement

You must install and configure the Splunk Add-on for AWS (version 5.1.0 or later) and Enterprise Security 6.2, which contains the required updates to the Authentication data model for cloud use cases. Run the Previously Seen Users in AWS CloudTrail - Initial support search only once to create a baseline of previously seen IAM users within the last 30 days. Run Previously Seen Users in AWS CloudTrail - Update hourly (or more frequently depending on how often you run the detection searches) to refresh the baselines. You can also provide additional filtering for this search by customizing the detect_aws_console_login_by_user_from_new_region_filter macro.

Known False Positives

When a legitimate new user logins for the first time, this activity will be detected. Check how old the account is and verify that the user activity is legitimate.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
36.0 60 60 User $user$ is logging into the AWS console from Region $Region$ for the first time

: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