Detection: Windows ESX Admins Group Creation via PowerShell

Updated Date: 2024-07-30 ID: f48a5557-be06-4b96-b8e8-be563e387620 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

This analytic detects attempts to create an "ESX Admins" group using PowerShell commands. This activity may indicate an attempt to exploit the VMware ESXi Active Directory Integration Authentication Bypass vulnerability (CVE-2024-37085). Attackers can use this method to gain unauthorized access to ESXi hosts by recreating the 'ESX Admins' group after its deletion from Active Directory.

Search

1`powershell` EventCode=4104 (ScriptBlockText="*New-ADGroup*" OR ScriptBlockText="*New-LocalGroup*") ScriptBlockText="*ESX Admins*" 
2| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer UserID 
3| rename Computer as dest 
4| rename UserID as user 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)` 
7| `windows_esx_admins_group_creation_via_powershell_filter`

Data Source

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

Macros Used

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

windows_esx_admins_group_creation_via_powershell_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
T1136.002	Domain Account	Persistence
T1136.001	Local Account	Persistence

KillChainPhase.INSTALLATION

NistCategory.DE_CM

Cis18Value.CIS_10

GALLIUM

HAFNIUM

Wizard Spider

APT3

APT39

APT41

APT5

Dragonfly

FIN13

Fox Kitten

Kimsuky

Leafminer

Magic Hound

TeamTNT

Wizard 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

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. You can find additional setup instructions in the Splunk documentation for configuring PowerShell logging.

Known False Positives

Legitimate administrators might create an "ESX Admins" group for valid reasons. Verify that the group creation is authorized and part of normal administrative tasks. Consider the context of the action, such as the user performing it and any related activities.

Associated Analytic Story

VMware ESXi AD Integration Authentication Bypass CVE-2024-37085

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
PowerShell command to create "ESX Admins" group detected on host $dest$ by user $user$.	56	80	70

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: 1