PowerShell Invoke CIMMethod CIMSession

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Description

This analytic identifies the use of the New-CIMSession cmdlet being created along with the Invoke-CIMMethod cmdlet being used within PowerShell. This particular behavior is similar to the usage of the Invoke-WMIMethod cmdlet, which is known for executing WMI commands on targets using NTLMv2 pass-the-hash authentication. The New-CIMSession cmdlet allows users to create a new CIM session object for a specified computer system, which can then be used to execute CIM operations remotely. Similarly, the Invoke-CIMMethod cmdlet is used to invoke a specified method on one or more CIM objects. Therefore, the combination of New-CIMSession and Invoke-CIMMethod cmdlets in PowerShell can potentially indicate malicious behavior, and this analytic can help detect such activity.

• Type: Anomaly

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

• Last Updated: 2023-03-22
• Author: Michael Haag, Splunk
• ID: 651ee958-a433-471c-b264-39725b788b83

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1047	Windows Management Instrumentation	Execution

Kill Chain Phase

• Installation

NIST

• DE.AE

CIS20

• CIS 10

CVE

Search

`powershell` EventCode=4104 ScriptBlockText IN ("*invoke-CIMMethod*", "*New-CimSession*") 
| stats count min(_time) as firstTime max(_time) as lastTime by Computer EventCode ScriptBlockText 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `powershell_invoke_cimmethod_cimsession_filter`

Macros

The SPL above uses the following Macros:

• powershell
• security_content_ctime

powershell_invoke_cimmethod_cimsession_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
• EventCode
• ScriptBlockText
• Computer

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

False positives may be present based on third-party applications or administrators using CIM. It is recommended to apply appropriate filters as needed to minimize the number of false positives.

Associated Analytic Story

• Malicious PowerShell
• Active Directory Lateral Movement

RBA

Risk Score	Impact	Confidence	Message
25.0	50	50	PowerShell was identified running a Invoke-CIMMethod Invoke-CIMSession on $Computer$.

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://learn.microsoft.com/en-us/powershell/module/cimcmdlets/invoke-cimmethod?view=powershell-7.3

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

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