PROD TM0121 - GPO - Enforced Outside of Tier Model | Microsoft Sentinel Analytic Rules

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Id	05846968-15cc-4309-bddc-eaa296f84af1
Rulename	PROD (TM012.1) - GPO - Enforced Outside of Tier Model
Description	Enforcing of a GPO could bypass or override Tier Model GPOs.
Severity	High
Tactics	DefenseEvasion
Techniques	T1484.001
Required data connectors	SecurityEvents WindowsSecurityEvents
Kind	Scheduled
Query frequency	5m
Query period	5m
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft%20Active%20Directory%20Tier%20Model/Analytic%20Rules/TM012_GPOEnforcedOutsideOfTierModel.yaml
Version	1.0.0
Arm template	05846968-15cc-4309-bddc-eaa296f84af1.json

KQL

SecurityEvent 
| where EventID == 5136 
    and not(EventData matches regex @"(?i)OU=Domain Controllers"
        or EventData matches regex @"(?i)OU=Tier 0 Member Servers"
        or EventData matches regex @"(?i)OU=Tier 1 Member Servers"
        or EventData matches regex @"(?i)OU=Tier 2 End-User Accounts"
        or EventData matches regex @"(?i)OU=Tier 2 End-User Devices"
        or EventData matches regex @"(?i)OU=Tier 2 End-User Groups"
        or EventData matches regex @"(?i)OU=Tier Model Administration"
        or EventData matches regex @"(?i)OU=Tier Model Computer Quarantine")
    and Activity has "modified" 
    and EventData has '"ObjectClass">organizationalUnit'
    and EventData has '<Data Name="AttributeLDAPDisplayName">gPLink</Data>' 
    and (EventData has ';0]' 
        or EventData has ';1]' 
        or EventData has ';2]')
    and EventData has '"OperationType">%%14674'
| extend ObjectName = extract("<Data Name=\"ObjectDN\">((?i)OU=[^,]+(,OU=[^,]+)*),(?i)DC=", 1, EventData)
| extend AttributeLDAP = extract("<Data Name=\"AttributeLDAPDisplayName\">([^<]+)</Data>", 1, EventData)
| extend AttributeValue = extract("\\[([^\\]]+)\\]", 1, EventData)
| extend LastThreeChars = substring(AttributeValue, strlen(AttributeValue) - 2, 3)
| extend AttributeValueDescription = case(
    LastThreeChars == ";0", "Linked",
    LastThreeChars == ";1", "Unlinked",
    LastThreeChars == ";2", "Enforced",
    "Unknown")
| where AttributeValueDescription == "Enforced"
| extend ObjectClass = extract("<Data Name=\"ObjectClass\">([^<]+)</Data>", 1, EventData)
| extend ObjectTier = "Outside Tier Model"
| extend Domain = extract("([^.]+\\.[^.]+)$", 1, Computer)
| project TimeGenerated
   , ObjectName
   , ObjectTier
   , ObjectClass
   , ActivityType = AttributeValueDescription
   , AttributeLDAP
   , Account
   , Domain
   , Computer
   , Channel
   , EventID
   , EventData

YAML

version: 1.0.0
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft%20Active%20Directory%20Tier%20Model/Analytic%20Rules/TM012_GPOEnforcedOutsideOfTierModel.yaml
triggerThreshold: 0
requiredDataConnectors:
- dataTypes:
  - SecurityEvent
  connectorId: SecurityEvents
- dataTypes:
  - SecurityEvent
  connectorId: WindowsSecurityEvents
tactics:
- DefenseEvasion
relevantTechniques:
- T1484.001
eventGroupingSettings:
  aggregationKind: AlertPerResult
incidentConfiguration:
  groupingConfiguration:
    matchingMethod: AllEntities
    lookbackDuration: PT5H
    reopenClosedIncident: false
    enabled: false
  createIncident: true
alertDetailsOverride:
  alertDescriptionFormat: Enforcing a GPO outside the Tier Model can overwrite and bypass Tier Model GPO with security controls.
  alertDisplayNameFormat: (TM012.1) A GPO was enforced and is overwriting the Tier Model GPOs
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: ObjectName
  entityType: Account
- fieldMappings:
  - identifier: HostName
    columnName: Computer
  entityType: Host
- fieldMappings:
  - identifier: FullName
    columnName: Account
  entityType: Account
description: |
  Enforcing of a GPO could bypass or override Tier Model GPOs.
triggerOperator: gt
kind: Scheduled
status: Available
queryFrequency: 5m
id: 05846968-15cc-4309-bddc-eaa296f84af1
name: PROD (TM012.1) - GPO - Enforced Outside of Tier Model
severity: High
query: |
  SecurityEvent 
  | where EventID == 5136 
      and not(EventData matches regex @"(?i)OU=Domain Controllers"
          or EventData matches regex @"(?i)OU=Tier 0 Member Servers"
          or EventData matches regex @"(?i)OU=Tier 1 Member Servers"
          or EventData matches regex @"(?i)OU=Tier 2 End-User Accounts"
          or EventData matches regex @"(?i)OU=Tier 2 End-User Devices"
          or EventData matches regex @"(?i)OU=Tier 2 End-User Groups"
          or EventData matches regex @"(?i)OU=Tier Model Administration"
          or EventData matches regex @"(?i)OU=Tier Model Computer Quarantine")
      and Activity has "modified" 
      and EventData has '"ObjectClass">organizationalUnit'
      and EventData has '<Data Name="AttributeLDAPDisplayName">gPLink</Data>' 
      and (EventData has ';0]' 
          or EventData has ';1]' 
          or EventData has ';2]')
      and EventData has '"OperationType">%%14674'
  | extend ObjectName = extract("<Data Name=\"ObjectDN\">((?i)OU=[^,]+(,OU=[^,]+)*),(?i)DC=", 1, EventData)
  | extend AttributeLDAP = extract("<Data Name=\"AttributeLDAPDisplayName\">([^<]+)</Data>", 1, EventData)
  | extend AttributeValue = extract("\\[([^\\]]+)\\]", 1, EventData)
  | extend LastThreeChars = substring(AttributeValue, strlen(AttributeValue) - 2, 3)
  | extend AttributeValueDescription = case(
      LastThreeChars == ";0", "Linked",
      LastThreeChars == ";1", "Unlinked",
      LastThreeChars == ";2", "Enforced",
      "Unknown")
  | where AttributeValueDescription == "Enforced"
  | extend ObjectClass = extract("<Data Name=\"ObjectClass\">([^<]+)</Data>", 1, EventData)
  | extend ObjectTier = "Outside Tier Model"
  | extend Domain = extract("([^.]+\\.[^.]+)$", 1, Computer)
  | project TimeGenerated
     , ObjectName
     , ObjectTier
     , ObjectClass
     , ActivityType = AttributeValueDescription
     , AttributeLDAP
     , Account
     , Domain
     , Computer
     , Channel
     , EventID
     , EventData
queryPeriod: 5m
customDetails:
  Computer: Computer
  EventData: EventData
  ObjectName: ObjectName
  EventID: EventID
  ObjectClass: ObjectClass
  ActivityType: ActivityType
  AttributeLDAP: AttributeLDAP
  Account: Account
  Channel: Channel
  Domain: Domain
  ObjectTier: ObjectTier

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/05846968-15cc-4309-bddc-eaa296f84af1')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/05846968-15cc-4309-bddc-eaa296f84af1')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "Enforcing a GPO outside the Tier Model can overwrite and bypass Tier Model GPO with security controls.",
          "alertDisplayNameFormat": "(TM012.1) A GPO was enforced and is overwriting the Tier Model GPOs"
        },
        "alertRuleTemplateName": "05846968-15cc-4309-bddc-eaa296f84af1",
        "customDetails": {
          "Account": "Account",
          "ActivityType": "ActivityType",
          "AttributeLDAP": "AttributeLDAP",
          "Channel": "Channel",
          "Computer": "Computer",
          "Domain": "Domain",
          "EventData": "EventData",
          "EventID": "EventID",
          "ObjectClass": "ObjectClass",
          "ObjectName": "ObjectName",
          "ObjectTier": "ObjectTier"
        },
        "description": "Enforcing of a GPO could bypass or override Tier Model GPOs.\n",
        "displayName": "PROD (TM012.1) - GPO - Enforced Outside of Tier Model",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "ObjectName",
                "identifier": "FullName"
              }
            ]
          },
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "Computer",
                "identifier": "HostName"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "Account",
                "identifier": "FullName"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "AlertPerResult"
        },
        "incidentConfiguration": {
          "createIncident": true,
          "groupingConfiguration": {
            "enabled": false,
            "lookbackDuration": "PT5H",
            "matchingMethod": "AllEntities",
            "reopenClosedIncident": false
          }
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft%20Active%20Directory%20Tier%20Model/Analytic%20Rules/TM012_GPOEnforcedOutsideOfTierModel.yaml",
        "query": "SecurityEvent \n| where EventID == 5136 \n    and not(EventData matches regex @\"(?i)OU=Domain Controllers\"\n        or EventData matches regex @\"(?i)OU=Tier 0 Member Servers\"\n        or EventData matches regex @\"(?i)OU=Tier 1 Member Servers\"\n        or EventData matches regex @\"(?i)OU=Tier 2 End-User Accounts\"\n        or EventData matches regex @\"(?i)OU=Tier 2 End-User Devices\"\n        or EventData matches regex @\"(?i)OU=Tier 2 End-User Groups\"\n        or EventData matches regex @\"(?i)OU=Tier Model Administration\"\n        or EventData matches regex @\"(?i)OU=Tier Model Computer Quarantine\")\n    and Activity has \"modified\" \n    and EventData has '\"ObjectClass\">organizationalUnit'\n    and EventData has '<Data Name=\"AttributeLDAPDisplayName\">gPLink</Data>' \n    and (EventData has ';0]' \n        or EventData has ';1]' \n        or EventData has ';2]')\n    and EventData has '\"OperationType\">%%14674'\n| extend ObjectName = extract(\"<Data Name=\\\"ObjectDN\\\">((?i)OU=[^,]+(,OU=[^,]+)*),(?i)DC=\", 1, EventData)\n| extend AttributeLDAP = extract(\"<Data Name=\\\"AttributeLDAPDisplayName\\\">([^<]+)</Data>\", 1, EventData)\n| extend AttributeValue = extract(\"\\\\[([^\\\\]]+)\\\\]\", 1, EventData)\n| extend LastThreeChars = substring(AttributeValue, strlen(AttributeValue) - 2, 3)\n| extend AttributeValueDescription = case(\n    LastThreeChars == \";0\", \"Linked\",\n    LastThreeChars == \";1\", \"Unlinked\",\n    LastThreeChars == \";2\", \"Enforced\",\n    \"Unknown\")\n| where AttributeValueDescription == \"Enforced\"\n| extend ObjectClass = extract(\"<Data Name=\\\"ObjectClass\\\">([^<]+)</Data>\", 1, EventData)\n| extend ObjectTier = \"Outside Tier Model\"\n| extend Domain = extract(\"([^.]+\\\\.[^.]+)$\", 1, Computer)\n| project TimeGenerated\n   , ObjectName\n   , ObjectTier\n   , ObjectClass\n   , ActivityType = AttributeValueDescription\n   , AttributeLDAP\n   , Account\n   , Domain\n   , Computer\n   , Channel\n   , EventID\n   , EventData\n",
        "queryFrequency": "PT5M",
        "queryPeriod": "PT5M",
        "severity": "High",
        "status": "Available",
        "subTechniques": [
          "T1484.001"
        ],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion"
        ],
        "techniques": [
          "T1484"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}