Detection: GetLocalUser with PowerShell Script Block

Updated Date: 2024-10-17 ID: 2e891cbe-0426-11ec-9c9c-acde48001122 Author: Mauricio Velazco, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects the execution of the Get-LocalUser PowerShell commandlet using PowerShell Script Block Logging (EventCode=4104). This commandlet lists all local users on a system. The detection leverages script block text from PowerShell logs to identify this activity. Monitoring this behavior is significant as adversaries and Red Teams may use it to enumerate local users for situational awareness and Active Directory discovery. If confirmed malicious, this activity could lead to further reconnaissance, enabling attackers to identify potential targets for privilege escalation or lateral movement.

Search

1`powershell` EventCode=4104 (ScriptBlockText = "*Get-LocalUser*") 
2| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer user_id 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `getlocaluser_with_powershell_script_block_filter`

Data Source

Name	Platform	Sourcetype	Source
Powershell Script Block Logging 4104	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Microsoft-Windows-PowerShell/Operational'`

Macros Used

Name	Value
powershell	`(source=WinEventLog:Microsoft-Windows-PowerShell/Operational OR source="XmlWinEventLog:Microsoft-Windows-PowerShell/Operational")`
getlocaluser_with_powershell_script_block_filter	`search *`

getlocaluser_with_powershell_script_block_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
T1087	Account Discovery	Discovery
T1087.001	Local Account	Discovery
T1059.001	PowerShell	Execution

KillChainPhase.EXPLOITAITON

KillChainPhase.INSTALLATION

NistCategory.DE_AE

Cis18Value.CIS_10

Aquatic Panda

FIN13

APT1

APT3

APT32

APT41

Chimera

Fox Kitten

Ke3chang

Moses Staff

OilRig

Poseidon Group

RedCurl

Threat Group-3390

Turla

Volt Typhoon

admin@338

APT19

APT28

APT29

APT3

APT32

APT33

APT38

APT39

APT41

APT5

Aquatic Panda

BRONZE BUTLER

Blue Mockingbird

CURIUM

Chimera

Cinnamon Tempest

Cobalt Group

Confucius

CopyKittens

Daggerfly

DarkHydrus

DarkVishnya

Deep Panda

Dragonfly

Earth Lusca

Ember Bear

FIN10

FIN13

FIN6

FIN7

FIN8

Fox Kitten

GALLIUM

GOLD SOUTHFIELD

Gallmaker

Gamaredon Group

Gorgon Group

HAFNIUM

HEXANE

Inception

Indrik Spider

Kimsuky

Lazarus Group

LazyScripter

Leviathan

Magic Hound

Molerats

MoustachedBouncer

MuddyWater

Mustang Panda

Nomadic Octopus

OilRig

Patchwork

Play

Poseidon Group

RedCurl

Saint Bear

Sandworm Team

Sidewinder

Silence

Stealth Falcon

TA2541

TA459

TA505

TeamTNT

Threat Group-3390

Thrip

ToddyCat

Tonto Team

Turla

Volt Typhoon

WIRTE

Winter Vivern

Wizard Spider

menuPass

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 Risk Event	False

This configuration file applies to all detections of type hunting.

Implementation

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.

Known False Positives

Administrators or power users may use this PowerShell commandlet for troubleshooting.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Local user discovery enumeration using PowerShell on $Computer$ by $user$	15	30	50

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

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-PowerShell/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-PowerShell/Operational`	`XmlWinEventLog`

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