ESXi Loghost Config Tampering

name: ESXi Loghost Config Tampering
id: 64bc2fa3-c493-44b4-8e94-3e5dbf71377e
version: 5
creation_date: '2025-07-11'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: TTP
description: This detection identifies changes to the syslog loghost configuration on an ESXi host, which may indicate an attempt to disrupt log forwarding and evade detection.
data_source:
    - VMWare ESXi Syslog
search: '`esxi_syslog` Message="*Set called with key*" AND Message IN ("*Syslog.global.logHost*","*Syslog.global.logdir*") | rex field=_raw "key ''(?<key>[^'']+)'', value ''\"(?<value>[^\"]+)\"''" | rex field=_raw "Z (?<dest>[\w\.]+)\s" | stats min(_time) as firstTime max(_time) as lastTime count by dest key value | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `esxi_loghost_config_tampering_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: Limited false positives in most environments, however tune as needed
finding:
    title: Syslog destination was modified on ESXi host $dest$.
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - ESXi Post Compromise
    - Black Basta Ransomware
asset_type: Infrastructure
mitre_attack_id:
    - T1685
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: application
security_domain: endpoint