Detection rules › Splunk

ESXi SSH Enabled

Status
production
Severity
medium
Group by
Message, dest
Author
Raven Tait, Splunk
Source
github.com/splunk/security_content

This detection identifies SSH being enabled on ESXi hosts, which can be an early indicator of malicious activity. Threat actors often use SSH to gain persistent remote access after compromising credentials or exploiting vulnerabilities.

Known false positives

  • Limited false positives in most environments, however tune as needed. Some Administrators may use SSH for troubleshooting.

MITRE ATT&CK coverage

TacticTechniques
Lateral Movement

Rule body

name: ESXi SSH Enabled
id: b8003567-c5b6-445b-8966-ecdacc81c24d
version: 5
creation_date: '2025-07-11'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: TTP
description: This detection identifies SSH being enabled on ESXi hosts, which can be an early indicator of malicious activity. Threat actors often use SSH to gain persistent remote access after compromising credentials or exploiting vulnerabilities.
data_source:
    - VMWare ESXi Syslog
search: '`esxi_syslog` Message="*SSH access has been enabled" | rex field=_raw "Z (?<dest>[\w\.]+)\s" | stats min(_time) as firstTime max(_time) as lastTime count by dest Message | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `esxi_ssh_enabled_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. Some Administrators may use SSH for troubleshooting.
finding:
    title: SSH was enabled on ESXi host $dest$.
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - ESXi Post Compromise
    - Black Basta Ransomware
    - Hellcat Ransomware
asset_type: Infrastructure
mitre_attack_id:
    - T1021.004
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: application
security_domain: endpoint

Stages and Predicates

Stage 1: search

`esxi_syslog` Message="*SSH access has been enabled"

Stage 2: rex

| rex field=_raw "Z (?<dest>[\w\.]+)\s"

Stage 3: stats

| stats min(_time) as firstTime max(_time) as lastTime count by dest Message

Stage 4: search

| `security_content_ctime(firstTime)`

Stage 5: search

| `security_content_ctime(lastTime)`

Stage 6: search

| `esxi_ssh_enabled_filter`

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Messageeq
  • "*SSH access has been enabled"
field:"Message" kind:eq
sourcetypein
  • vmw-syslog
  • vmware:esxlog*
field:"sourcetype" kind:in