: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 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. Deprecated now this search is updated to use the Authentication datamodel.

  • Type: Hunting
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2020-07-21
  • Author: Bhavin Patel, Splunk
  • ID: ada0f478-84a8-4641-a3f3-d82362dffd75

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1078.004 Cloud Accounts Defense Evasion, Persistence, Privilege Escalation, Initial Access
Kill Chain Phase
  • Actions on Objectives
NIST
  • DE.DP
  • DE.AE
CIS20
  • CIS 16
CVE
1
2
3
4
5
6
7
8
9
10
`cloudtrail` eventName=ConsoleLogin 
| rename userIdentity.arn as user 
| stats earliest(_time) as firstTime latest(_time) as lastTime by user 
| inputlookup append=t previously_seen_users_console_logins_cloudtrail  
| stats min(firstTime) as firstTime max(lastTime) as lastTime by user 
| eval userStatus=if(firstTime >= relative_time(now(), "-70m@m"), "First Time Logging into AWS Console","Previously Seen User") 
| `security_content_ctime(firstTime)`
|`security_content_ctime(lastTime)`
| where userStatus ="First Time Logging into AWS Console"  
| `detect_new_user_aws_console_login_filter`

Macros

The SPL above uses the following Macros:

:information_source: detect_new_user_aws_console_login_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
  • userIdentity.arn

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. Run the "Previously seen users in AWS CloudTrail" support search only once to create a baseline of previously seen IAM users within the last 30 days. Run "Update previously seen users in AWS CloudTrail" hourly (or more frequently depending on how often you run the detection searches) to refresh the baselines.

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
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