Detection: Short Lived Windows Accounts

Updated Date: 2024-05-14 ID: b25f6f62-0782-43c1-b403-083231ffd97d Author: David Dorsey, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the rapid creation and deletion of Windows accounts within a short time frame. It leverages the "Change" data model in Splunk, specifically monitoring events with result IDs 4720 (account creation) and 4726 (account deletion). This behavior is significant as it may indicate an attacker attempting to create and remove accounts quickly to evade detection or gain unauthorized access. If confirmed malicious, this activity could lead to unauthorized access, privilege escalation, or further malicious actions within the environment. Immediate investigation of flagged events is crucial to mitigate potential damage.

Search

1
2| tstats `security_content_summariesonly` values(All_Changes.result_id) as result_id count min(_time) as firstTime max(_time) as lastTime from datamodel=Change where All_Changes.result_id=4720 OR All_Changes.result_id=4726 by _time span=4h All_Changes.user All_Changes.dest 
3| `security_content_ctime(lastTime)` 
4| `security_content_ctime(firstTime)` 
5| `drop_dm_object_name("All_Changes")` 
6| search result_id = 4720 result_id=4726 
7| transaction user connected=false maxspan=240m 
8| table firstTime lastTime count user dest result_id 
9| `short_lived_windows_accounts_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Windows Event Log System 4720	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:System'`	N/A

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
short_lived_windows_accounts_filter	`search *`

short_lived_windows_accounts_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1136.001	Local Account	Persistence
T1136	Create Account	Persistence

KillChainPhase.INSTALLATION

NistCategory.DE_CM

Cis18Value.CIS_10

APT3

APT39

APT41

APT5

Dragonfly

FIN13

Fox Kitten

Kimsuky

Leafminer

Magic Hound

TeamTNT

Wizard Spider

Indrik Spider

Scattered Spider

Default Configuration

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

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

This search requires you to have enabled your Group Management Audit Logs in your Local Windows Security Policy and be ingesting those logs. More information on how to enable them can be found here: http://whatevernetworks.com/auditing-group-membership-changes-in-active-directory/

Known False Positives

It is possible that an administrator created and deleted an account in a short time period. Verifying activity with an administrator is advised.

Associated Analytic Story

Active Directory Lateral Movement

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
A user account created or delete shortly in host $dest$	63	70	90

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`WinEventLog:Security`	`WinEventLog`
Integration	✅ Passing	Dataset	`WinEventLog:Security`	`WinEventLog`

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: 4