Guest accounts added in Entra ID Groups other than the ones specified

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Id	6ab1f7b2-61b8-442f-bc81-96afe7ad8c53
Rulename	Guest accounts added in Entra ID Groups other than the ones specified
Description	Guest Accounts are added in the Organization Tenants to perform various tasks i.e projects execution, support etc.. This detection notifies when guest users are added to Microsoft Entra ID Groups other than the ones specified and poses a risk to gain access to sensitive apps or data.
Severity	High
Tactics	InitialAccess Persistence Discovery
Techniques	T1078.004 T1136.003 T1087.004
Required data connectors	AzureActiveDirectory
Kind	Scheduled
Query frequency	2h
Query period	2h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/GuestAccountsAddedinAADGroupsOtherThanTheOnesSpecified.yaml
Version	1.0.6
Arm template	6ab1f7b2-61b8-442f-bc81-96afe7ad8c53.json

KQL

// OBJECT ID of AAD Groups can be found by navigating to Azure Active Directory then from menu on the left, select Groups and from the list shown of AAD Groups, the Second Column shows the ObjectID of each
let GroupIDs = dynamic(["List with Custom AAD GROUP OBJECT ID 1","Custom AAD GROUP OBJECT ID 2"]);
AuditLogs
| where OperationName in ('Add member to group', 'Add owner to group')
| extend InitiatingAppName = tostring(InitiatedBy.app.displayName)
| extend InitiatingAppServicePrincipalId = tostring(InitiatedBy.app.servicePrincipalId)
| extend InitiatingUserPrincipalName = tostring(InitiatedBy.user.userPrincipalName)
| extend InitiatingAadUserId = tostring(InitiatedBy.user.id)
| extend InitiatingIpAddress = tostring(iff(isnotempty(InitiatedBy.user.ipAddress), InitiatedBy.user.ipAddress, InitiatedBy.app.ipAddress))
// Uncomment the following line to filter events where the inviting user was a guest user
//| where InitiatedBy has_any ("CUSTOM DOMAIN NAME#", "#EXT#")
| mv-apply TargetResource = TargetResources on 
  (
      where TargetResource.type =~ "User"
      | extend InvitedUserPrincipalName = trim(@'"',tostring(TargetResource.userPrincipalName)),
               Properties = TargetResource.modifiedProperties
  )
| mv-apply Property = Properties on 
  (
      where Property.displayName =~ "Group.DisplayName"
      | extend AADGroup = trim('"',tostring(Property.newValue))
  )
| where InvitedUserPrincipalName has_any ("CUSTOM DOMAIN NAME#", "#EXT#")
| mv-apply Property = Properties on
   (
     where Property.displayName =~ "Group.ObjectID"
     | extend AADGroupId = trim('"',tostring(Property.newValue))
   )
| project-away TargetResource, Property
| where AADGroupId !in (GroupIDs)
| extend Name = tostring(split(InitiatingUserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(InitiatingUserPrincipalName,'@',1)[0])
| extend InvitedUserName = tostring(split(InvitedUserPrincipalName,'@',0)[0]), InvitedUPNSuffix = tostring(split(InvitedUserPrincipalName,'@',1)[0])

YAML

severity: High
relevantTechniques:
- T1078.004
- T1136.003
- T1087.004
queryFrequency: 2h
kind: Scheduled
version: 1.0.6
name: Guest accounts added in Entra ID Groups other than the ones specified
triggerOperator: gt
description: |
    'Guest Accounts are added in the Organization Tenants to perform various tasks i.e projects execution, support etc.. This detection notifies when guest users are added to Microsoft Entra ID Groups other than the ones specified and poses a risk to gain access to sensitive apps or data.'
queryPeriod: 2h
query: |
  // OBJECT ID of AAD Groups can be found by navigating to Azure Active Directory then from menu on the left, select Groups and from the list shown of AAD Groups, the Second Column shows the ObjectID of each
  let GroupIDs = dynamic(["List with Custom AAD GROUP OBJECT ID 1","Custom AAD GROUP OBJECT ID 2"]);
  AuditLogs
  | where OperationName in ('Add member to group', 'Add owner to group')
  | extend InitiatingAppName = tostring(InitiatedBy.app.displayName)
  | extend InitiatingAppServicePrincipalId = tostring(InitiatedBy.app.servicePrincipalId)
  | extend InitiatingUserPrincipalName = tostring(InitiatedBy.user.userPrincipalName)
  | extend InitiatingAadUserId = tostring(InitiatedBy.user.id)
  | extend InitiatingIpAddress = tostring(iff(isnotempty(InitiatedBy.user.ipAddress), InitiatedBy.user.ipAddress, InitiatedBy.app.ipAddress))
  // Uncomment the following line to filter events where the inviting user was a guest user
  //| where InitiatedBy has_any ("CUSTOM DOMAIN NAME#", "#EXT#")
  | mv-apply TargetResource = TargetResources on 
    (
        where TargetResource.type =~ "User"
        | extend InvitedUserPrincipalName = trim(@'"',tostring(TargetResource.userPrincipalName)),
                 Properties = TargetResource.modifiedProperties
    )
  | mv-apply Property = Properties on 
    (
        where Property.displayName =~ "Group.DisplayName"
        | extend AADGroup = trim('"',tostring(Property.newValue))
    )
  | where InvitedUserPrincipalName has_any ("CUSTOM DOMAIN NAME#", "#EXT#")
  | mv-apply Property = Properties on
     (
       where Property.displayName =~ "Group.ObjectID"
       | extend AADGroupId = trim('"',tostring(Property.newValue))
     )
  | project-away TargetResource, Property
  | where AADGroupId !in (GroupIDs)
  | extend Name = tostring(split(InitiatingUserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(InitiatingUserPrincipalName,'@',1)[0])
  | extend InvitedUserName = tostring(split(InvitedUserPrincipalName,'@',0)[0]), InvitedUPNSuffix = tostring(split(InvitedUserPrincipalName,'@',1)[0])  
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: InvitedUserPrincipalName
    identifier: FullName
  - columnName: InvitedUserName
    identifier: Name
  - columnName: InvitedUPNSuffix
    identifier: UPNSuffix
- entityType: Account
  fieldMappings:
  - columnName: InitiatingUserPrincipalName
    identifier: FullName
  - columnName: Name
    identifier: Name
  - columnName: UPNSuffix
    identifier: UPNSuffix
- entityType: Account
  fieldMappings:
  - columnName: InitiatingAadUserId
    identifier: AadUserId
- entityType: Account
  fieldMappings:
  - columnName: InitiatingAppServicePrincipalId
    identifier: AadUserId
- entityType: IP
  fieldMappings:
  - columnName: InitiatingIpAddress
    identifier: Address
- entityType: SecurityGroup
  fieldMappings:
  - columnName: AADGroup
    identifier: DistinguishedName
  - columnName: AADGroupId
    identifier: ObjectGuid
tactics:
- InitialAccess
- Persistence
- Discovery
status: Available
triggerThreshold: 0
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/GuestAccountsAddedinAADGroupsOtherThanTheOnesSpecified.yaml
id: 6ab1f7b2-61b8-442f-bc81-96afe7ad8c53
requiredDataConnectors:
- dataTypes:
  - AuditLogs
  connectorId: AzureActiveDirectory

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/6ab1f7b2-61b8-442f-bc81-96afe7ad8c53')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/6ab1f7b2-61b8-442f-bc81-96afe7ad8c53')]",
      "properties": {
        "alertRuleTemplateName": "6ab1f7b2-61b8-442f-bc81-96afe7ad8c53",
        "customDetails": null,
        "description": "'Guest Accounts are added in the Organization Tenants to perform various tasks i.e projects execution, support etc.. This detection notifies when guest users are added to Microsoft Entra ID Groups other than the ones specified and poses a risk to gain access to sensitive apps or data.'\n",
        "displayName": "Guest accounts added in Entra ID Groups other than the ones specified",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "InvitedUserPrincipalName",
                "identifier": "FullName"
              },
              {
                "columnName": "InvitedUserName",
                "identifier": "Name"
              },
              {
                "columnName": "InvitedUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "InitiatingUserPrincipalName",
                "identifier": "FullName"
              },
              {
                "columnName": "Name",
                "identifier": "Name"
              },
              {
                "columnName": "UPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "InitiatingAadUserId",
                "identifier": "AadUserId"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "InitiatingAppServicePrincipalId",
                "identifier": "AadUserId"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "InitiatingIpAddress",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "SecurityGroup",
            "fieldMappings": [
              {
                "columnName": "AADGroup",
                "identifier": "DistinguishedName"
              },
              {
                "columnName": "AADGroupId",
                "identifier": "ObjectGuid"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/GuestAccountsAddedinAADGroupsOtherThanTheOnesSpecified.yaml",
        "query": "// OBJECT ID of AAD Groups can be found by navigating to Azure Active Directory then from menu on the left, select Groups and from the list shown of AAD Groups, the Second Column shows the ObjectID of each\nlet GroupIDs = dynamic([\"List with Custom AAD GROUP OBJECT ID 1\",\"Custom AAD GROUP OBJECT ID 2\"]);\nAuditLogs\n| where OperationName in ('Add member to group', 'Add owner to group')\n| extend InitiatingAppName = tostring(InitiatedBy.app.displayName)\n| extend InitiatingAppServicePrincipalId = tostring(InitiatedBy.app.servicePrincipalId)\n| extend InitiatingUserPrincipalName = tostring(InitiatedBy.user.userPrincipalName)\n| extend InitiatingAadUserId = tostring(InitiatedBy.user.id)\n| extend InitiatingIpAddress = tostring(iff(isnotempty(InitiatedBy.user.ipAddress), InitiatedBy.user.ipAddress, InitiatedBy.app.ipAddress))\n// Uncomment the following line to filter events where the inviting user was a guest user\n//| where InitiatedBy has_any (\"CUSTOM DOMAIN NAME#\", \"#EXT#\")\n| mv-apply TargetResource = TargetResources on \n  (\n      where TargetResource.type =~ \"User\"\n      | extend InvitedUserPrincipalName = trim(@'\"',tostring(TargetResource.userPrincipalName)),\n               Properties = TargetResource.modifiedProperties\n  )\n| mv-apply Property = Properties on \n  (\n      where Property.displayName =~ \"Group.DisplayName\"\n      | extend AADGroup = trim('\"',tostring(Property.newValue))\n  )\n| where InvitedUserPrincipalName has_any (\"CUSTOM DOMAIN NAME#\", \"#EXT#\")\n| mv-apply Property = Properties on\n   (\n     where Property.displayName =~ \"Group.ObjectID\"\n     | extend AADGroupId = trim('\"',tostring(Property.newValue))\n   )\n| project-away TargetResource, Property\n| where AADGroupId !in (GroupIDs)\n| extend Name = tostring(split(InitiatingUserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(InitiatingUserPrincipalName,'@',1)[0])\n| extend InvitedUserName = tostring(split(InvitedUserPrincipalName,'@',0)[0]), InvitedUPNSuffix = tostring(split(InvitedUserPrincipalName,'@',1)[0])\n",
        "queryFrequency": "PT2H",
        "queryPeriod": "PT2H",
        "severity": "High",
        "status": "Available",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Discovery",
          "InitialAccess",
          "Persistence"
        ],
        "techniques": [
          "T1078",
          "T1087",
          "T1136"
        ],
        "templateVersion": "1.0.6",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}