Detection rules › Splunk

Windows Suspicious VMWare Tools Child Process

Status
production
Severity
medium
Group by
IntegrityLevel, command_line, computer_name, event_action, original_file_name, parent_command_line, parent_process_guid, parent_process_id, parent_process_name, process_guid, process_hash, process_id, process_name, user, user_id, vendor_product
Author
Raven Tait, Splunk
Source
github.com/splunk/security_content

The following analytic identifies child processes spawned by vmtoolsd.exe, the VMWare Tools service in Windows, which typically runs with SYSTEM privileges. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and parent process relationships. Monitoring this activity is crucial as it can indicate exploitation attempts, such as CVE-2023-20867. If confirmed malicious, attackers could gain SYSTEM-level access, allowing them to execute arbitrary code, escalate privileges, and potentially compromise the entire system.

Known false positives

  • Although unlikely, some legitimate Administrative scripts may utilize VMWare Tools to execute commands on virtual machines.

MITRE ATT&CK coverage

Telemetry coverage

Rule body

name: Windows Suspicious VMWare Tools Child Process
id: 1f77661a-0fe3-4b8d-a62c-7dff06906d26
version: 5
creation_date: '2022-02-09'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: TTP
description: The following analytic identifies child processes spawned by vmtoolsd.exe, the VMWare Tools service in Windows, which typically runs with SYSTEM privileges. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and parent process relationships. Monitoring this activity is crucial as it can indicate exploitation attempts, such as CVE-2023-20867. If confirmed malicious, attackers could gain SYSTEM-level access, allowing them to execute arbitrary code, escalate privileges, and potentially compromise the entire system.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: "| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes\n  WHERE Processes.parent_process_name=vmtoolsd.exe\n    AND\n    Processes.process_name IN (\"powershell.exe\",\"cmd.exe\", \"msbuild.exe\", \"microsoft.workflow.compiler.exe\", \"searchprotocolhost.exe\", \"scrcons.exe\", \"cscript.exe\", \"wscript.exe\",\"bitsadmin.exe\", \"rundll32.exe\", \"wmic.exe\", \"mshta.exe\", \"certutil.exe\", \"schtasks.exe\")\n    AND NOT\n    (Processes.process_name=\"cmd.exe\" AND Processes.process IN (\"*\\\\VMware Tools\\\\poweroff-vm-default.bat*\",\"*\\\\VMware Tools\\\\poweron-vm-default.bat*\"))\n  BY Processes.action Processes.dest Processes.original_file_name\n     Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid\n     Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path\n     Processes.process Processes.process_exec Processes.process_guid\n     Processes.process_hash Processes.process_id Processes.process_integrity_level\n     Processes.process_name Processes.process_path Processes.user\n     Processes.user_id Processes.vendor_product\n| `drop_dm_object_name(Processes)`\n| `security_content_ctime(firstTime)`\n| `security_content_ctime(lastTime)`\n| `windows_suspicious_vmware_tools_child_process_filter`"
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: Although unlikely, some legitimate Administrative scripts may utilize VMWare Tools to execute commands on virtual machines.
references:
    - https://cloud.google.com/blog/topics/threat-intelligence/vmware-esxi-zero-day-bypass/
finding:
    title: Suspicious process spawned by vmtoolsd.exe on $dest$
    entity:
        field: dest
        type: system
        score: 50
threat_objects:
    - field: parent_process_name
      type: parent_process_name
analytic_story:
    - ESXi Post Compromise
    - China-Nexus Threat Activity
asset_type: Endpoint
cve:
    - CVE-2023-20867
mitre_attack_id:
    - T1059
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint

Stages and Predicates

Stage 1: tstats

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
  WHERE Processes.parent_process_name=vmtoolsd.exe
    AND
    Processes.process_name IN ("powershell.exe","cmd.exe", "msbuild.exe", "microsoft.workflow.compiler.exe", "searchprotocolhost.exe", "scrcons.exe", "cscript.exe", "wscript.exe","bitsadmin.exe", "rundll32.exe", "wmic.exe", "mshta.exe", "certutil.exe", "schtasks.exe")
    AND NOT
    (Processes.process_name="cmd.exe" AND Processes.process IN ("*\\VMware Tools\\poweroff-vm-default.bat*","*\\VMware Tools\\poweron-vm-default.bat*"))
  BY Processes.action Processes.dest Processes.original_file_name
     Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
     Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
     Processes.process Processes.process_exec Processes.process_guid
     Processes.process_hash Processes.process_id Processes.process_integrity_level
     Processes.process_name Processes.process_path Processes.user
     Processes.user_id Processes.vendor_product

Stage 2: search

| `drop_dm_object_name(Processes)`

Stage 3: search

| `security_content_ctime(firstTime)`

Stage 4: search

| `security_content_ctime(lastTime)`

Stage 5: search

| `windows_suspicious_vmware_tools_child_process_filter`

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
Processes.processin"*\\VMware Tools\\poweroff-vm-default.bat*", "*\\VMware Tools\\poweron-vm-default.bat*"excludes:Processes.process
Processes.process_nameeq"cmd.exe"excludes:Processes.process_name

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Processes.parent_process_nameeq
  • "vmtoolsd.exe"
field:"parent_process_name" kind:eq
Processes.process_namein
  • "bitsadmin.exe" corpus 23 (elastic 21, splunk 2)
  • "certutil.exe" corpus 44 (elastic 38, splunk 6)
  • "cmd.exe" corpus 121 (elastic 92, splunk 29)
  • "cscript.exe" corpus 67 (elastic 65, splunk 2)
  • "microsoft.workflow.compiler.exe" corpus 12 (elastic 11, splunk 1)
  • "msbuild.exe" corpus 39 (elastic 36, splunk 3)
  • "mshta.exe" corpus 84 (elastic 79, splunk 5)
  • "powershell.exe" corpus 184 (elastic 140, splunk 44)
  • "rundll32.exe" corpus 126 (elastic 100, splunk 26)
  • "schtasks.exe" corpus 30 (elastic 19, splunk 11)
  • "scrcons.exe"
  • "searchprotocolhost.exe" corpus 6 (elastic 4, splunk 2)
  • "wmic.exe" corpus 66 (elastic 39, splunk 27)
  • "wscript.exe" corpus 83 (elastic 82, splunk 1)
field:"process_name" kind:in