Detection rules › Splunk

ESXi VM Exported via Remote Tool

Status
production
Severity
medium
Group by
Datastore, InitiatorIP, InitiatorTool, ToolVersion, VMPath, dest
Author
Raven Tait, Splunk
Source
github.com/splunk/security_content

This detection identifies the use of a remote tool to download virtual machine disk files from a datastore. The NFC protocol is used by management tools to transfer files to and from ESXi hosts, but it can also be abused by attackers or insiders to exfiltrate full virtual disk images

Known false positives

  • Administrators may use this command when troubleshooting. Tune as needed.

MITRE ATT&CK coverage

TacticTechniques
Collection

Rule body

name: ESXi VM Exported via Remote Tool
id: 2e155547-aaac-49d3-b0ef-ceabc31fd364
version: 4
creation_date: '2025-07-11'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: TTP
description: This detection identifies the use of a remote tool to download virtual machine disk files from a datastore. The NFC protocol is used by management tools to transfer files to and from ESXi hosts, but it can also be abused by attackers or insiders to exfiltrate full virtual disk images
data_source:
    - VMWare ESXi Syslog
search: '`esxi_syslog` Message="*File download from path*" Message="*was initiated from*" | rex field=_raw "from path ''\[(?<Datastore>[^\]]+)\](?<VMPath>[^'']+)''" | rex field=_raw "initiated from ''(?<InitiatorTool>[^/]+)/(?<ToolVersion>[^@]+)@(?<InitiatorIP>\d{1,3}(?:\.\d{1,3}){3})''" | rex field=_raw "Z (?<dest>[\w\.]+)\s" | stats min(_time) as firstTime max(_time) as lastTime count by Datastore VMPath InitiatorTool ToolVersion InitiatorIP dest | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `esxi_vm_exported_via_remote_tool_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: Administrators may use this command when troubleshooting. Tune as needed.
finding:
    title: VM downloaded from datastore 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:
    - T1005
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: application
security_domain: endpoint

Stages and Predicates

Stage 1: search

`esxi_syslog` Message="*File download from path*" Message="*was initiated from*"

Stage 2: rex

| rex field=_raw "from path '\[(?<Datastore>[^\]]+)\](?<VMPath>[^']+)'"

Stage 3: rex

| rex field=_raw "initiated from '(?<InitiatorTool>[^/]+)/(?<ToolVersion>[^@]+)@(?<InitiatorIP>\d{1,3}(?:\.\d{1,3}){3})'"

Stage 4: rex

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

Stage 5: stats

| stats min(_time) as firstTime max(_time) as lastTime count by Datastore VMPath InitiatorTool ToolVersion InitiatorIP dest

Stage 6: search

| `security_content_ctime(firstTime)`

Stage 7: search

| `security_content_ctime(lastTime)`

Stage 8: search

| `esxi_vm_exported_via_remote_tool_filter`

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Messageeq
  • "*File download from path*"
  • "*was initiated from*"
field:"Message" kind:eq
sourcetypein
  • vmw-syslog
  • vmware:esxlog*
field:"sourcetype" kind:in