Detection: Detect AWS Console Login by User from New Region

Description

The following analytic identifies AWS console login attempts by users from a new region. It leverages AWS CloudTrail events and compares current login regions against a baseline of previously seen regions for each user. This activity is significant as it may indicate unauthorized access attempts or compromised credentials. If confirmed malicious, an attacker could gain unauthorized access to AWS resources, potentially leading to data breaches, resource manipulation, or further lateral movement within the cloud environment.

Search

 1
 2| tstats earliest(_time) as firstTime latest(_time) as lastTime from datamodel=Authentication where Authentication.signature=ConsoleLogin by Authentication.user Authentication.src 
 3| iplocation Authentication.src 
 4| `drop_dm_object_name(Authentication)` 
 5| rename Region as justSeenRegion 
 6| table firstTime lastTime user justSeenRegion 
 7| join user type=outer [
 8| inputlookup previously_seen_users_console_logins 
 9| rename Region as previouslySeenRegion 
10| stats min(firstTime) AS earliestseen by user previouslySeenRegion 
11| fields earliestseen user previouslySeenRegion] 
12| eval userRegion=if(firstTime >= relative_time(now(), "-24h@h"), "New Region","Previously Seen Region") 
13| where userRegion= "New Region" 
14| `security_content_ctime(firstTime)` 
15| `security_content_ctime(lastTime)` 
16| table firstTime lastTime user previouslySeenRegion justSeenRegion userRegion 
17| `detect_aws_console_login_by_user_from_new_region_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
AWS CloudTrail	AWS	'aws:cloudtrail'	'aws_cloudtrail'	N/A

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

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

• AWS Identity and Access Management Account Takeover

• Compromised User Account

• Suspicious AWS Login Activities

• Suspicious Cloud Authentication Activities

Risk Based Analytics (RBA)

Detection Testing

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: GitHub | Version: 3