Cross-tenant Access Settings Organization Added

// Tenants IDs can be found by navigating to Azure Active Directory then from menu on the left, select External Identities, then from menu on the left, select Cross-tenant access settings and from the list shown of Tenants
let ExpectedTenantIDs = dynamic(["List of expected tenant IDs","Tenant ID 2"]);
AuditLogs
| where OperationName has "Add a partner to cross-tenant access setting"
| mv-apply TargetResource = TargetResources on
  (
      where TargetResource.type =~ "Policy"
      | extend Properties = TargetResource.modifiedProperties
  )
| mv-apply Property = Properties on
  (
      where Property.displayName =~ "tenantId"
      | extend ExtTenantIDAdded = trim('"',tostring(Property.newValue))
  )
| where ExtTenantIDAdded !in (ExpectedTenantIDs)
| 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))
| extend InitiatingAccountName = tostring(split(InitiatingUserPrincipalName, "@")[0]), InitiatingAccountUPNSuffix = tostring(split(InitiatingUserPrincipalName, "@")[1])

tactics:
- InitialAccess
- Persistence
- Discovery
relevantTechniques:
- T1078.004
- T1136.003
- T1087.004
status: Available
severity: Medium
name: Cross-tenant Access Settings Organization Added
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - AuditLogs
query: |
  // Tenants IDs can be found by navigating to Azure Active Directory then from menu on the left, select External Identities, then from menu on the left, select Cross-tenant access settings and from the list shown of Tenants
  let ExpectedTenantIDs = dynamic(["List of expected tenant IDs","Tenant ID 2"]);
  AuditLogs
  | where OperationName has "Add a partner to cross-tenant access setting"
  | mv-apply TargetResource = TargetResources on
    (
        where TargetResource.type =~ "Policy"
        | extend Properties = TargetResource.modifiedProperties
    )
  | mv-apply Property = Properties on
    (
        where Property.displayName =~ "tenantId"
        | extend ExtTenantIDAdded = trim('"',tostring(Property.newValue))
    )
  | where ExtTenantIDAdded !in (ExpectedTenantIDs)
  | 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))
  | extend InitiatingAccountName = tostring(split(InitiatingUserPrincipalName, "@")[0]), InitiatingAccountUPNSuffix = tostring(split(InitiatingUserPrincipalName, "@")[1])  
id: 757e6a79-6d23-4ae6-9845-4dac170656b5
queryPeriod: 2d
entityMappings:
- entityType: Account
  fieldMappings:
  - identifier: Name
    columnName: InitiatingAppName
  - identifier: AadUserId
    columnName: InitiatingAppServicePrincipalId
- entityType: Account
  fieldMappings:
  - identifier: FullName
    columnName: InitiatingUserPrincipalName
  - identifier: Name
    columnName: InitiatingAccountName
  - identifier: UPNSuffix
    columnName: InitiatingAccountUPNSuffix
- entityType: Account
  fieldMappings:
  - identifier: AadUserId
    columnName: InitiatingAadUserId
- entityType: IP
  fieldMappings:
  - identifier: Address
    columnName: InitiatingIpAddress
triggerOperator: gt
triggerThreshold: 0
description: |
    'Organizations are added in the Cross-tenant Access Settings to control communication inbound or outbound for users and applications. This detection notifies when an Organization is added other than the list that is supposed to exist from the Microsoft Entra ID Cross-tenant Access Settings.'
version: 1.1.1
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/Cross-tenantAccessSettingsOrganizationAdded.yaml
queryFrequency: 2d
kind: Scheduled

{
  "$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/757e6a79-6d23-4ae6-9845-4dac170656b5')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/757e6a79-6d23-4ae6-9845-4dac170656b5')]",
      "properties": {
        "alertRuleTemplateName": "757e6a79-6d23-4ae6-9845-4dac170656b5",
        "customDetails": null,
        "description": "'Organizations are added in the Cross-tenant Access Settings to control communication inbound or outbound for users and applications. This detection notifies when an Organization is added other than the list that is supposed to exist from the Microsoft Entra ID Cross-tenant Access Settings.'\n",
        "displayName": "Cross-tenant Access Settings Organization Added",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "InitiatingAppName",
                "identifier": "Name"
              },
              {
                "columnName": "InitiatingAppServicePrincipalId",
                "identifier": "AadUserId"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "InitiatingUserPrincipalName",
                "identifier": "FullName"
              },
              {
                "columnName": "InitiatingAccountName",
                "identifier": "Name"
              },
              {
                "columnName": "InitiatingAccountUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "InitiatingAadUserId",
                "identifier": "AadUserId"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "InitiatingIpAddress",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Entra ID/Analytic Rules/Cross-tenantAccessSettingsOrganizationAdded.yaml",
        "query": "// Tenants IDs can be found by navigating to Azure Active Directory then from menu on the left, select External Identities, then from menu on the left, select Cross-tenant access settings and from the list shown of Tenants\nlet ExpectedTenantIDs = dynamic([\"List of expected tenant IDs\",\"Tenant ID 2\"]);\nAuditLogs\n| where OperationName has \"Add a partner to cross-tenant access setting\"\n| mv-apply TargetResource = TargetResources on\n  (\n      where TargetResource.type =~ \"Policy\"\n      | extend Properties = TargetResource.modifiedProperties\n  )\n| mv-apply Property = Properties on\n  (\n      where Property.displayName =~ \"tenantId\"\n      | extend ExtTenantIDAdded = trim('\"',tostring(Property.newValue))\n  )\n| where ExtTenantIDAdded !in (ExpectedTenantIDs)\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| extend InitiatingAccountName = tostring(split(InitiatingUserPrincipalName, \"@\")[0]), InitiatingAccountUPNSuffix = tostring(split(InitiatingUserPrincipalName, \"@\")[1])\n",
        "queryFrequency": "P2D",
        "queryPeriod": "P2D",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [
          "T1078.004",
          "T1136.003",
          "T1087.004"
        ],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Discovery",
          "InitialAccess",
          "Persistence"
        ],
        "techniques": [
          "T1078",
          "T1087",
          "T1136"
        ],
        "templateVersion": "1.1.1",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}