Detection rules › Splunk
ESXi Loghost Config Tampering
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.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Defense Impairment | T1685 Disable or Modify Tools |
Rule body splunk
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
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 ("$dest$") | 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: 7d
latest_offset: "0"
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
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1562.003/esxi_loghost_config_tampering/esxi_loghost_config_tampering.log
source: vmware:esxlog
sourcetype: vmw-syslog
test_type: unit
Stages and Predicates
Stage 1: search
`esxi_syslog` Message="*Set called with key*" AND Message IN ("*Syslog.global.logHost*","*Syslog.global.logdir*")
Stage 2: eval
| rex field=_raw "key '(?<key>[^']+)', value '\"(?<value>[^\"]+)\"'"
Stage 3: rex
| rex field=_raw "Z (?<dest>[\w\.]+)\s"
Stage 4: stats
| stats min(_time) as firstTime max(_time) as lastTime count by dest key value
Stage 5: search
| `security_content_ctime(firstTime)`
Stage 6: search
| `security_content_ctime(lastTime)`
Stage 7: search
| `esxi_loghost_config_tampering_filter`
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
Message | eq |
|
Message | in |
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sourcetype | in |
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