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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: 2020-10-07
  • Author: Bhavin Patel, Splunk
  • ID: 67bd3def-c41c-4bf6-837b-ae196b4257c6

Annotations

ATT&CK
ID Technique Tactic
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)` 
| table firstTime lastTime user Country 
| join user  type=outer [
| inputlookup previously_seen_users_console_logins 
| stats min(firstTime) AS earliestseen by user Country 
| fields earliestseen user Country] 
| eval userCountry=if(firstTime >= relative_time(now(), "-24h@h"), "New Country","Previously Seen Country") 
| eval userStatus=if(earliestseen >= relative_time(now(),"-24h@h") OR isnull(earliestseen), "New User","Old User") 
| where userCountry = "New Country" AND userStatus != "Old User" 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| table firstTime lastTime user Country  userStatus userCountry  
| `detect_aws_console_login_by_user_from_new_country_filter`

Macros

The SPL above uses the following Macros:

Note that detect_aws_console_login_by_user_from_new_country_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 field

  • _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_country_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
42.0 70 60 User $user$ is logging into the AWS console from Country $Country$ for the first time

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

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