splunk_escuAnomaly

ESXi Account Modified

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.

MITRE ATT&CK

T1136.001 T1078 T1098

Detection Query

`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`

Author

Raven Tait, Splunk

Created

2026-03-10

Data Sources

VMWare ESXi Syslog

References

https://detect.fyi/detecting-and-responding-to-esxi-compromise-with-splunk-f33998ce7823

Tags

ESXi Post CompromiseBlack Basta Ransomware

Raw Content

name: ESXi Account Modified
id: b5e3b024-a7bb-4019-8975-46cf54485e78
version: 2
date: '2026-03-10'
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
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168  | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: Local account created, deleted, or modified on ESXi $dest$.
    risk_objects:
        - field: dest
          type: system
          score: 20
    threat_objects: []
tags:
    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
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1098/esxi_account_modification/esxi_account_modified.log
          source: vmware:esxlog
          sourcetype: vmw-syslog