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Detection rules › Kusto

Tenable.ad Indicators of Exposures

Severity
low
Time window
2h
Group by
Severity
Source
github.com/Azure/Azure-Sentinel

'Searches for triggered Indicators of Exposures.'

MITRE ATT&CK coverage

TacticTechniques
Credential Access

Rule body

id: 55de1072-e93f-40f9-a14d-f7356d217cf6
name: Tenable.ad Indicators of Exposures
description: |
    'Searches for triggered Indicators of Exposures.'
severity: Low
requiredDataConnectors:
  - connectorId: Tenable.ad
    dataTypes:
      - Tenable_ad_CL
queryFrequency: 2h
queryPeriod: 2h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CredentialAccess
relevantTechniques:
  - T1110
query: |
  // For the query to work properly, make sure you have imported the afad_parser.kql parser into the workspace
  // Retrieve the parser here: https://raw.githubusercontent.com/tenable/Azure-Sentinel/Tenable.ad-connector/Solutions/TenableAD/Parsers/afad_parser.kql
  // Then, create the Kusto Function with alias afad_parser
  let SeverityTable=datatable(Severity:string,Level:int) [
    "low", 1,
    "medium", 2,
    "high", 3,
    "critical", 4
    ];
    afad_parser
    | where MessageType == 0
    | lookup kind=leftouter SeverityTable on Severity
    | order by Level
    | extend HostName = tostring(split(Host, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Host, '.'), 1, -1), '.'))
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
version: 1.0.1
kind: Scheduled

Stages and Predicates

Let binding: SeverityTable used in Stage 3

let SeverityTable = datatable(Severity:string,Level:int) [
  "low", 1,
  "medium", 2,
  "high", 3,
  "critical", 4
  ];

Stage 1: source

afad_parser

Stage 2: where

| where MessageType == 0

Stage 3: kusto:lookup

| lookup kind=leftouter SeverityTable on Severity

Stage 4: sort

| order by Level

Stage 5: extend

| extend HostName = tostring(split(Host, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Host, '.'), 1, -1), '.'))

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
MessageTypeeq
  • 0 corpus 15 (kusto 15)
field:"MessageType" kind:eq value:"0"

Output fields

These fields are emitted when the rule matches.

FieldSource
DnsDomainextend
HostNameextend