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Detection rules › Kusto

VMware ESXi - Root login

Status
available
Severity
high
Time window
14d
Source
github.com/Azure/Azure-Sentinel

'Detects when root user login from uncommon IP address.'

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1078 Valid Accounts
Privilege EscalationT1078 Valid Accounts

Rule body kusto

id: deb448a8-6a9d-4f8c-8a95-679a0a2cd62c
name: VMware ESXi - Root login
description: |
  'Detects when root user login from uncommon IP address.'
severity: High
status: Available
requiredDataConnectors:
  - connectorId: SyslogAma
    datatypes:
      - Syslog
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
  - PrivilegeEscalation
relevantTechniques:
  - T1078
query: |
  let p_lookback = 14d;
  let t_lookback = 1h;
  let root_ips = VMwareESXi
  | where TimeGenerated between (ago(p_lookback) .. ago(t_lookback))
  | where SyslogMessage has_all ('UserLoginSessionEvent', 'root', 'logged in')
  | extend SrcIpAddr = extract(@'root@(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})', 1, SyslogMessage)
  | summarize makeset(SrcIpAddr);
  VMwareESXi
  | where TimeGenerated > ago(t_lookback)
  | where SyslogMessage has_all ('UserLoginSessionEvent', 'root', 'logged in')
  | extend SrcIpAddr = extract(@'root@(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})', 1, SyslogMessage)
  | where SrcIpAddr !in (root_ips)
  | extend IPCustomEntity = SrcIpAddr
entityMappings:
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IPCustomEntity
version: 1.0.3
kind: Scheduled

Stages and Predicates

Parameters

let p_lookback = 14d;
let t_lookback = 1h;

Let binding: root_ips

let root_ips = VMwareESXi
| where TimeGenerated between (ago(p_lookback) .. ago(t_lookback))
| where SyslogMessage has_all ('UserLoginSessionEvent', 'root', 'logged in')
| extend SrcIpAddr = extract(@'root@(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})', 1, SyslogMessage)
| summarize makeset(SrcIpAddr);

Derived from p_lookback, t_lookback.

Stage 1: source

VMwareESXi

Stage 2: where

| where TimeGenerated > ago(t_lookback)

Stage 3: where

| where SyslogMessage has_all ('UserLoginSessionEvent', 'root', 'logged in')

Stage 4: extend

| extend SrcIpAddr = extract(@'root@(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})', 1, SyslogMessage)

Stage 5: where

| where SrcIpAddr !in (root_ips)

References root_ips (defined above).

Stage 6: extend

| extend IPCustomEntity = SrcIpAddr

Exclusions

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

FieldKindExcluded values
SrcIpAddreqroot_ips

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
  • UserLoginSessionEvent
  • logged in
  • root

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
SrcIpAddrextend
IPCustomEntityextend