User Discovery And Export Via Get-ADUser Cmdlet

Status: test
Severity: medium
Log source: category process_creation, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects usage of the Get-ADUser cmdlet to collect user information and output it to a file

Known false positives

Legitimate admin scripts may use the same technique, it's better to exclude specific computers or users who execute these commands or scripts often

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1033` System Owner/User Discovery

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: User Discovery And Export Via Get-ADUser Cmdlet
id: 1114e048-b69c-4f41-bc20-657245ae6e3f
related:
    - id: c2993223-6da8-4b1a-88ee-668b8bf315e9
      type: similar
status: test
description: Detects usage of the Get-ADUser cmdlet to collect user information and output it to a file
references:
    - http://blog.talosintelligence.com/2022/09/lazarus-three-rats.html
    - https://www.microsoft.com/en-us/security/blog/2022/10/18/defenders-beware-a-case-for-post-ransomware-investigations/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-09-09
modified: 2022-11-17
tags:
    - attack.discovery
    - attack.t1033
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_cli:
        CommandLine|contains|all:
            - 'Get-ADUser '
            - ' -Filter \*'
        CommandLine|contains:
            - ' > '
            - ' | Select '
            - 'Out-File'
            - 'Set-Content'
            - 'Add-Content'
    condition: all of selection_*
falsepositives:
    - Legitimate admin scripts may use the same technique, it's better to exclude specific computers or users who execute these commands or scripts often
level: medium

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith:
          - '\powershell.exe'
          - '\pwsh.exe'
    - OriginalFileName:
          - 'PowerShell.EXE'
          - 'pwsh.dll'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains|all:
        - 'Get-ADUser '
        - ' -Filter \*'
    CommandLine|contains:
        - ' > '
        - ' | Select '
        - 'Out-File'
        - 'Set-Content'
        - 'Add-Content'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`-Filter \*` corpus 2 (sigma 2) `>` corpus 5 (sigma 5) `\| Select` corpus 2 (sigma 2) `Add-Content` corpus 2 (sigma 2) `Get-ADUser` `Out-File` corpus 3 (sigma 3) `Set-Content` corpus 2 (sigma 2)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\powershell.exe` corpus 179 (sigma 178, kusto 1) `\pwsh.exe` corpus 165 (sigma 164, kusto 1)	`field:"Image" kind:ends_with`
`OriginalFileName`	eq	`PowerShell.EXE` corpus 138 (sigma 84, splunk 30, elastic 24) `pwsh.dll` corpus 112 (sigma 79, splunk 30, elastic 3)	`field:"OriginalFileName" kind:eq`

User Discovery And Export Via Get-ADUser Cmdlet

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli`