ESXi Account Modified

name: ESXi Account Modified
id: b5e3b024-a7bb-4019-8975-46cf54485e78
version: 4
creation_date: '2025-07-11'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: Anomaly
description: This detection identifies the creation, deletion, or modification of a local user account on an ESXi host. This activity may indicate unauthorized access, indicator removal, or persistence attempts by an attacker seeking to establish or maintain control of the host.
data_source:
    - VMWare ESXi Syslog
search: '`esxi_syslog` Message="*esxcli system account*" Message IN ("*-i *","*--id*") NOT Message="*[shell*" | rex field=_raw "Z (?<dest>[\w\.]+)\s.*: \[(?<initial_user>\w+)]:\s.+-i[d]*\s(?<modified_user>[\w_\-0-9]+)" | stats min(_time) as firstTime max(_time) as lastTime count by dest initial_user modified_user | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `esxi_account_modified_filter`'
how_to_implement: 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: New local accounts being created in ESXi is rare in most environments. Tune as needed.
references:
    - https://detect.fyi/detecting-and-responding-to-esxi-compromise-with-splunk-f33998ce7823
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: Local account created, deleted, or modified on ESXi $dest$.
analytic_story:
    - ESXi Post Compromise
    - Black Basta Ransomware
asset_type: Infrastructure
mitre_attack_id:
    - T1136.001
    - T1078
    - T1098
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: application
security_domain: endpoint