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Detection rules › Kusto

VMware ESXi - New VM started

Status
available
Severity
medium
Time window
1h
Source
github.com/Azure/Azure-Sentinel

'Detects when new VM was started.'

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1078 Valid Accounts

Rule body kusto

id: 0f4a80de-344f-47c0-bc19-cb120c59b6f0
name: VMware ESXi - New VM started
description: |
  'Detects when new VM was started.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: SyslogAma
    datatypes:
      - Syslog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1078
query: |
  let a_vm = 
  VMwareESXi
  | where SyslogMessage has ('VmPoweredOnEvent')
  | extend DstHostname = extract(@'\[\d+\]\s+\[(.*?)\s+on', 1, SyslogMessage)
  | summarize vm_l = makeset(DstHostname)
  | extend k=1;
  VMwareESXi
  | where SyslogMessage has ('VmPoweredOnEvent')
  | extend DstHostname = extract(@'\[\d+\]\s+\[(.*?)\s+on', 1, SyslogMessage)
  | extend k = 1
  | join (a_vm) on k
  | where vm_l !has DstHostname
  | extend HostCustomEntity = DstHostname
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: HostCustomEntity
version: 1.0.2
kind: Scheduled

Stages and Predicates

Let binding: a_vm

let a_vm = VMwareESXi
| where SyslogMessage has ('VmPoweredOnEvent')
| extend DstHostname = extract(@'\[\d+\]\s+\[(.*?)\s+on', 1, SyslogMessage)
| summarize vm_l = makeset(DstHostname)
| extend k=1;

Stage 1: source

VMwareESXi

Stage 2: where

| where SyslogMessage has ('VmPoweredOnEvent')

Stage 3: extend

| extend DstHostname = extract(@'\[\d+\]\s+\[(.*?)\s+on', 1, SyslogMessage)

Stage 4: extend

| extend k = 1

Stage 5: join

| join (a_vm) on k

Stage 6: where

| where vm_l !has DstHostname

Stage 7: extend

| extend HostCustomEntity = DstHostname

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
vm_lmatchDstHostname

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.

FieldKindValues
SyslogMessagematch
  • VmPoweredOnEvent transforms: term

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
DstHostnameextend
kextend
HostCustomEntityextend