Microsoft Entra ID Local Device Join Information and Transport Key Registry Keys Access

id: a356c8bd-c81d-428b-aa36-83be706be034
name: Microsoft Entra ID Local Device Join Information and Transport Key Registry Keys Access 
description: |
  'This detection uses Windows security events to detect suspicious access attempts by the same process to registry keys that provide information about an Microsoft Entra ID joined or registered devices and Transport keys (tkpub / tkpriv).
   This information can be used to export the Device Certificate (dkpub / dkpriv) and Transport key (tkpub/tkpriv).
   These set of keys can be used to impersonate existing Microsoft Entra ID joined devices.
   This detection requires an access control entry (ACE) on the system access control list (SACL) of the following securable objects:
   HKLM:\SYSTEM\CurrentControlSet\Control\CloudDomainJoin (Microsoft Entra ID joined devices)
   HKCU:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\WorkplaceJoin (Microsoft Entra ID registered devices)
   HKLM:\SYSTEM\CurrentControlSet\Control\Cryptography\Ngc\KeyTransportKey (Transport Key)
   Make sure you set the SACL to propagate to its sub-keys. You can find more information in here https://github.com/OTRF/Set-AuditRule/blob/master/rules/registry/aad_connect_health_service_agent.yml
   Reference: https://aadinternals.com/post/deviceidentity/'
severity: Medium
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
  - connectorId: WindowsSecurityEvents
    dataTypes:
      - SecurityEvent
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
status: Available
tactics:
  - Discovery
relevantTechniques:
  - T1012
tags:
  - SimuLand
  - ATR
  - AADInternals
query: |
  // AADJoined or Register Device Registry Keys
  let aadJoinRoot = "\\REGISTRY\\MACHINE\\SYSTEM\\ControlSet001\\Control\\CloudDomainJoin\\JoinInfo\\";
  let aadRegisteredRoot = "\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\WorkplaceJoin";
  // Transport Key Registry Key
  let keyTransportKey = "\\REGISTRY\\MACHINE\\SYSTEM\\ControlSet001\\Control\\Cryptography\\Ngc\\KeyTransportKey\\";
  (union isfuzzy=true
  (
  // Access to Object Requested
  SecurityEvent
  | where EventID == '4656'
  | where EventData has aadJoinRoot or EventData has aadRegisteredRoot
  | extend EventData = parse_xml(EventData).EventData.Data
  | mv-expand bagexpansion=array EventData
  | evaluate bag_unpack(EventData)
  | extend Key = tostring(column_ifexists('@Name', "")), Value = column_ifexists('#text', "")
  | evaluate pivot(Key, any(Value), TimeGenerated, Computer, EventID)
  | where ObjectType == 'Key'
  | where ObjectName startswith aadJoinRoot and SubjectLogonId != '0x3e7' //Local System
  | extend ProcessId = column_ifexists("ProcessId", ""), Process = split(ProcessName, '\\', -1)[-1],Account = strcat(SubjectDomainName, "\\", SubjectUserName)
  | join kind=innerunique (
      SecurityEvent
      | where EventID == '4656'
      | where EventData has keyTransportKey
      | extend EventData = parse_xml(EventData).EventData.Data
      | mv-expand bagexpansion=array EventData
      | evaluate bag_unpack(EventData)
      | extend Key = tostring(column_ifexists('@Name', "")), Value = column_ifexists('#text', "")
      | evaluate pivot(Key, any(Value), TimeGenerated, Computer, EventID)
      | extend ObjectName = column_ifexists("ObjectName", ""),ObjectType = column_ifexists("ObjectType", "")
      | where ObjectType == 'Key'
      | where ObjectName startswith keyTransportKey and SubjectLogonId != '0x3e7' //Local System
      | extend ProcessId = column_ifexists("ProcessId", ""), Process = split(ProcessName, '\\', -1)[-1],Account = strcat(SubjectDomainName, "\\", SubjectUserName)
  ) on $left.Computer == $right.Computer and $left.SubjectLogonId == $right.SubjectLogonId and $left.ProcessId == $right.ProcessId
  | project TimeGenerated, Computer, Account, SubjectDomainName, SubjectUserName, SubjectLogonId, ObjectName, tostring(Process), ProcessName, ProcessId, EventID
  ),
  // Accessing Object
  (
  SecurityEvent
  | where EventID == '4663'
  | where ObjectType == 'Key'
  | where (ObjectName startswith aadJoinRoot or ObjectName contains aadRegisteredRoot) and SubjectLogonId != '0x3e7' //Local System
  | extend Account = SubjectAccount
  | join kind=innerunique (
      SecurityEvent
      | where EventID == '4663'
      | where ObjectType == 'Key'
      | where ObjectName has keyTransportKey and SubjectLogonId != '0x3e7' //Local System
      | extend Account = SubjectAccount
  ) on $left.Computer == $right.Computer and $left.SubjectLogonId == $right.SubjectLogonId and $left.ProcessId == $right.ProcessId
  | project TimeGenerated, Computer, Account, SubjectDomainName, SubjectUserName, SubjectLogonId, ObjectName, Process, ProcessName, ProcessId, EventID
  | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
  )
  )
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: Account
      - identifier: Name
        columnName: SubjectUserName
      - identifier: NTDomain
        columnName: SubjectDomainName
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Computer
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
version: 1.0.6
kind: Scheduled