Detection: Windows ESX Admins Group Creation via Net

Updated Date: 2024-07-30 ID: 3d7df60b-3332-4667-8090-afe03e08dce0 Author: Michael Haag, Splunk Type: TTP Product: Splunk Enterprise Security

Description

This analytic detects attempts to create an "ESX Admins" group using the Windows net.exe or net1.exe 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.

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where (Processes.process_name="net.exe" OR Processes.process_name="net1.exe") AND (Processes.process="*group \"ESX Admins\"*" OR Processes.process="*group ESX Admins*") AND Processes.process="*/add*" by Processes.dest Processes.user Processes.parent_process_name Processes.parent_process Processes.process_name Processes.process Processes.process_id Processes.original_file_name 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_esx_admins_group_creation_via_net_filter`

Data Source

Name Platform Sourcetype Source Supported App
Sysmon EventID 1 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' N/A

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_esx_admins_group_creation_via_net_filter search *
windows_esx_admins_group_creation_via_net_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 search, you need to be ingesting data that records process activity from your hosts to populate the Endpoint data model in the Processes node. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

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

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
An attempt to create an "ESX Admins" group was detected on $dest$ 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-Sysmon/Operational xmlwineventlog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/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