GetWmiObject Ds Computer with PowerShell Script Block

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Description

The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify the execution of the Get-WmiObject commandlet. The DS_Computer class parameter leverages WMI to query for all domain computers. Red Teams and adversaries may leverage this commandlet to enumerate domain computers for situational awareness and Active Directory Discovery.

• Type: TTP

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

• Last Updated: 2022-05-02
• Author: Mauricio Velazco, Splunk
• ID: 29b99201-723c-4118-847a-db2b3d3fb8ea

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1018	Remote System Discovery	Discovery

Kill Chain Phase

• Reconnaissance

NIST

CIS20

CVE

Search

`powershell` EventCode=4104 (ScriptBlockText=*Get-WmiObject* AND ScriptBlockText="*namespace root\\directory\\ldap*" AND ScriptBlockText="*class ds_computer*") 
| stats count min(_time) as firstTime max(_time) as lastTime by Opcode Computer UserID EventCode ScriptBlockText 
| `security_content_ctime(firstTime)` 
| `getwmiobject_ds_computer_with_powershell_script_block_filter`

Macros

The SPL above uses the following Macros:

• powershell
• security_content_ctime

getwmiobject_ds_computer_with_powershell_script_block_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
• ScriptBlockText
• Opcode
• Computer
• UserID
• EventCode

How To Implement

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

• Active Directory Discovery

RBA

Risk Score	Impact	Confidence	Message
15.0	30	50	Remote system discovery enumeration on $Computer$ by $UserID$

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

• https://attack.mitre.org/techniques/T1018/
• https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.management/get-wmiobject?view=powershell-5.1

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059.001/powershell_script_block_logging/sbl_xml.log

source | version: 2