Azure Portal sign in from another Azure Tenant

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Id	87210ca1-49a4-4a7d-bb4a-4988752f978c
Rulename	Azure Portal sign in from another Azure Tenant
Description	This query looks for successful sign in attempts to the Azure Portal where the user who is signing in from another Azure tenant, and the IP address the login attempt is from is an Azure IP. A threat actor who compromises an Azure tenant may look to pivot to other tenants leveraging cross-tenant delegated access in this manner.
Severity	Medium
Tactics	InitialAccess
Techniques	T1199
Required data connectors	AzureActiveDirectory
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Azure Active Directory/Analytic Rules/AzurePortalSigninfromanotherAzureTenant.yaml
Version	2.0.1
Arm template	87210ca1-49a4-4a7d-bb4a-4988752f978c.json

KQL

// Get details of current Azure Ranges (note this URL updates regularly so will need to be manually updated over time)
// You may find the name of the new JSON here: https://www.microsoft.com/download/details.aspx?id=56519
// On the downloads page, click the 'details' button, and then replace just the filename in the URL below
let azure_ranges = externaldata(changeNumber: string, cloud: string, values: dynamic)
["https://raw.githubusercontent.com/microsoft/mstic/master/PublicFeeds/MSFTIPRanges/ServiceTags_Public.json"] with(format='multijson')
| mv-expand values
| mv-expand values.properties.addressPrefixes
| mv-expand values_properties_addressPrefixes
| summarize by tostring(values_properties_addressPrefixes)
| extend isipv4 = parse_ipv4(values_properties_addressPrefixes)
| extend isipv6 = parse_ipv6(values_properties_addressPrefixes)
| extend ip_type = case(isnotnull(isipv4), "v4", "v6")
| summarize make_list(values_properties_addressPrefixes) by ip_type
;
SigninLogs
// Limiting to Azure Portal really reduces false positives and helps focus on potential admin activity
| where ResultType == 0
| where AppDisplayName =~ "Azure Portal"
| extend isipv4 = parse_ipv4(IPAddress)
| extend ip_type = case(isnotnull(isipv4), "v4", "v6")
 // Only get logons where the IP address is in an Azure range
| join kind=fullouter (azure_ranges) on ip_type
| extend ipv6_match = ipv6_is_in_any_range(IPAddress,  list_values_properties_addressPrefixes)
| extend ipv4_match = ipv4_is_in_any_range(IPAddress,  list_values_properties_addressPrefixes)
| where ipv4_match or ipv6_match 
// Limit to where the user is external to the tenant
| where HomeTenantId != ResourceTenantId
// Further limit it to just access to the current tenant (you can drop this if you wanted to look elsewhere as well but it helps reduce FPs)
| where ResourceTenantId == AADTenantId
| summarize FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated), make_set(ResourceDisplayName) by UserPrincipalName, IPAddress, UserAgent, Location, HomeTenantId, ResourceTenantId, UserId
| extend AccountName = split(UserPrincipalName, "@")[0]
| extend UPNSuffix = split(UserPrincipalName, "@")[1]

YAML

triggerOperator: gt
version: 2.0.1
query: |
  // Get details of current Azure Ranges (note this URL updates regularly so will need to be manually updated over time)
  // You may find the name of the new JSON here: https://www.microsoft.com/download/details.aspx?id=56519
  // On the downloads page, click the 'details' button, and then replace just the filename in the URL below
  let azure_ranges = externaldata(changeNumber: string, cloud: string, values: dynamic)
  ["https://raw.githubusercontent.com/microsoft/mstic/master/PublicFeeds/MSFTIPRanges/ServiceTags_Public.json"] with(format='multijson')
  | mv-expand values
  | mv-expand values.properties.addressPrefixes
  | mv-expand values_properties_addressPrefixes
  | summarize by tostring(values_properties_addressPrefixes)
  | extend isipv4 = parse_ipv4(values_properties_addressPrefixes)
  | extend isipv6 = parse_ipv6(values_properties_addressPrefixes)
  | extend ip_type = case(isnotnull(isipv4), "v4", "v6")
  | summarize make_list(values_properties_addressPrefixes) by ip_type
  ;
  SigninLogs
  // Limiting to Azure Portal really reduces false positives and helps focus on potential admin activity
  | where ResultType == 0
  | where AppDisplayName =~ "Azure Portal"
  | extend isipv4 = parse_ipv4(IPAddress)
  | extend ip_type = case(isnotnull(isipv4), "v4", "v6")
   // Only get logons where the IP address is in an Azure range
  | join kind=fullouter (azure_ranges) on ip_type
  | extend ipv6_match = ipv6_is_in_any_range(IPAddress,  list_values_properties_addressPrefixes)
  | extend ipv4_match = ipv4_is_in_any_range(IPAddress,  list_values_properties_addressPrefixes)
  | where ipv4_match or ipv6_match 
  // Limit to where the user is external to the tenant
  | where HomeTenantId != ResourceTenantId
  // Further limit it to just access to the current tenant (you can drop this if you wanted to look elsewhere as well but it helps reduce FPs)
  | where ResourceTenantId == AADTenantId
  | summarize FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated), make_set(ResourceDisplayName) by UserPrincipalName, IPAddress, UserAgent, Location, HomeTenantId, ResourceTenantId, UserId
  | extend AccountName = split(UserPrincipalName, "@")[0]
  | extend UPNSuffix = split(UserPrincipalName, "@")[1]  
status: Available
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: AccountName
    identifier: Name
  - columnName: UPNSuffix
    identifier: UPNSuffix
  - columnName: UserId
    identifier: AadUserId
- entityType: IP
  fieldMappings:
  - columnName: IPAddress
    identifier: Address
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Azure Active Directory/Analytic Rules/AzurePortalSigninfromanotherAzureTenant.yaml
queryFrequency: 1h
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - SigninLogs
name: Azure Portal sign in from another Azure Tenant
queryPeriod: 1h
severity: Medium
kind: Scheduled
tactics:
- InitialAccess
id: 87210ca1-49a4-4a7d-bb4a-4988752f978c
description: |
  'This query looks for successful sign in attempts to the Azure Portal where the user who is signing in from another Azure tenant,
   and the IP address the login attempt is from is an Azure IP. A threat actor who compromises an Azure tenant may look
   to pivot to other tenants leveraging cross-tenant delegated access in this manner.'  
relevantTechniques:
- T1199
triggerThreshold: 0
alertDetailsOverride:
  alertDescriptionFormat: |
    This query looks for successful sign in attempts to the Azure Portal where the user who is signing in from another Azure tenant,
    and the IP address the login attempt is from is an Azure IP. A threat actor who compromises an Azure tenant may look
    to pivot to other tenants leveraging cross-tenant delegated access in this manner.
    In this instance {{UserPrincipalName}} logged in at {{FirstSeen}} from IP Address {{IPAddress}}.    
  alertDisplayNameFormat: Azure Portal sign in by {{UserPrincipalName}} from another Azure Tenant with IP Address {{IPAddress}}

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/87210ca1-49a4-4a7d-bb4a-4988752f978c')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/87210ca1-49a4-4a7d-bb4a-4988752f978c')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01-preview",
      "properties": {
        "displayName": "Azure Portal sign in from another Azure Tenant",
        "description": "'This query looks for successful sign in attempts to the Azure Portal where the user who is signing in from another Azure tenant,\n and the IP address the login attempt is from is an Azure IP. A threat actor who compromises an Azure tenant may look\n to pivot to other tenants leveraging cross-tenant delegated access in this manner.'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "// Get details of current Azure Ranges (note this URL updates regularly so will need to be manually updated over time)\n// You may find the name of the new JSON here: https://www.microsoft.com/download/details.aspx?id=56519\n// On the downloads page, click the 'details' button, and then replace just the filename in the URL below\nlet azure_ranges = externaldata(changeNumber: string, cloud: string, values: dynamic)\n[\"https://raw.githubusercontent.com/microsoft/mstic/master/PublicFeeds/MSFTIPRanges/ServiceTags_Public.json\"] with(format='multijson')\n| mv-expand values\n| mv-expand values.properties.addressPrefixes\n| mv-expand values_properties_addressPrefixes\n| summarize by tostring(values_properties_addressPrefixes)\n| extend isipv4 = parse_ipv4(values_properties_addressPrefixes)\n| extend isipv6 = parse_ipv6(values_properties_addressPrefixes)\n| extend ip_type = case(isnotnull(isipv4), \"v4\", \"v6\")\n| summarize make_list(values_properties_addressPrefixes) by ip_type\n;\nSigninLogs\n// Limiting to Azure Portal really reduces false positives and helps focus on potential admin activity\n| where ResultType == 0\n| where AppDisplayName =~ \"Azure Portal\"\n| extend isipv4 = parse_ipv4(IPAddress)\n| extend ip_type = case(isnotnull(isipv4), \"v4\", \"v6\")\n // Only get logons where the IP address is in an Azure range\n| join kind=fullouter (azure_ranges) on ip_type\n| extend ipv6_match = ipv6_is_in_any_range(IPAddress,  list_values_properties_addressPrefixes)\n| extend ipv4_match = ipv4_is_in_any_range(IPAddress,  list_values_properties_addressPrefixes)\n| where ipv4_match or ipv6_match \n// Limit to where the user is external to the tenant\n| where HomeTenantId != ResourceTenantId\n// Further limit it to just access to the current tenant (you can drop this if you wanted to look elsewhere as well but it helps reduce FPs)\n| where ResourceTenantId == AADTenantId\n| summarize FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated), make_set(ResourceDisplayName) by UserPrincipalName, IPAddress, UserAgent, Location, HomeTenantId, ResourceTenantId, UserId\n| extend AccountName = split(UserPrincipalName, \"@\")[0]\n| extend UPNSuffix = split(UserPrincipalName, \"@\")[1]\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1199"
        ],
        "alertRuleTemplateName": "87210ca1-49a4-4a7d-bb4a-4988752f978c",
        "alertDetailsOverride": {
          "alertDescriptionFormat": "This query looks for successful sign in attempts to the Azure Portal where the user who is signing in from another Azure tenant,\nand the IP address the login attempt is from is an Azure IP. A threat actor who compromises an Azure tenant may look\nto pivot to other tenants leveraging cross-tenant delegated access in this manner.\nIn this instance {{UserPrincipalName}} logged in at {{FirstSeen}} from IP Address {{IPAddress}}.\n",
          "alertDisplayNameFormat": "Azure Portal sign in by {{UserPrincipalName}} from another Azure Tenant with IP Address {{IPAddress}}"
        },
        "customDetails": null,
        "entityMappings": [
          {
            "fieldMappings": [
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "UPNSuffix",
                "identifier": "UPNSuffix"
              },
              {
                "columnName": "UserId",
                "identifier": "AadUserId"
              }
            ],
            "entityType": "Account"
          },
          {
            "fieldMappings": [
              {
                "columnName": "IPAddress",
                "identifier": "Address"
              }
            ],
            "entityType": "IP"
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Azure Active Directory/Analytic Rules/AzurePortalSigninfromanotherAzureTenant.yaml",
        "status": "Available",
        "templateVersion": "2.0.1"
      }
    }
  ]
}