Detection: ESXi User Granted Admin Role

Description

This detection identifies when a user is granted the Administrator role on an ESXi host. Assigning elevated privileges is a critical action that can indicate potential malicious behavior if performed unexpectedly. Adversaries who gain access may use this to escalate privileges, maintain persistence, or disable security controls.

1`esxi_syslog` Message="*esxcli system permission set*" AND Message="*role Admin*" 
2| rex field=_raw "\]: \[(?<user>\w+)\]:(?<command>.+)" 
3| rex field=_raw "--id (?<target_user>\w+)" 
4| rex field=_raw "Z (?<dest>[\w\.]+)\s" 
5| stats min(_time) as firstTime max(_time) as lastTime count by dest user command target_user 
6| `security_content_ctime(firstTime)` 
7| `security_content_ctime(lastTime)` 
8| `esxi_user_granted_admin_role_filter`

Data Source

Name Platform Sourcetype Source
VMWare ESXi Syslog N/A 'vmw-syslog' 'vmware:esxlog'

Macros Used

Name Value
esxi_syslog sourcetype=vmw-syslog OR sourcetype=vmware:esxlog*
esxi_user_granted_admin_role_filter search *
esxi_user_granted_admin_role_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
T1098 Account Manipulation Persistence
T1078 Valid Accounts Privilege Escalation
Delivery
Exploitation
Installation
DE.CM
CIS 10

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

This is based on syslog data generated by VMware ESXi hosts. To implement this search, you must configure your ESXi systems to forward syslog output to your Splunk deployment. These logs must be ingested with the appropriate Splunk Technology Add-on for VMware ESXi Logs, which provides field extractions and CIM compatibility.

Known False Positives

Limited false positives in most environments after initial setup, however tune as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

$target_user$ granted Admin role on ESXi host $dest$ by $user$.

Risk Object Risk Object Type Risk Score Threat Objects
target_user user 60 No Threat Objects
dest system 60 No Threat Objects

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation Passing N/A N/A N/A
Unit Passing Dataset vmware:esxlog vmw-syslog
Integration ✅ Passing Dataset vmware:esxlog vmw-syslog

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