Add ADF outbound access control via Azure Policy to prevent data exfiltration

research-spoke/spoke-modules/airlock/adf.bicep

@@ -29,6 +29,9 @@ param pipelineNameFilesToFiles string = 'pipe-data_move-files_to_files'
 
 param debugMode bool
 
+@description('The names of additional storage accounts (beyond the private storage account) that the Data Factory is allowed to access via its pipelines. Used to configure outbound access control.')
+param allowedStorageAccountNames array = []
+
 import { pipelineNamesType } from '../../../shared-modules/types/pipelineNamesType.bicep'
 
 var baseName = !empty(subWorkloadName)
@@ -41,6 +44,20 @@ var adlsGen2LinkedServiceName = 'ls_ADLSGen2_Generic'
 var azFilesLinkedServiceName = 'ls_AzFiles_Generic'
 var kvLinkedServiceName = 'ls_KeyVault'
 
+// Outbound access control: compute the list of allowed domain names for the Azure Policy assignment
+var storageSuffix = environment().suffixes.storage
+var keyVaultSuffix = environment().suffixes.keyvaultDns
+// Combine the private storage account with any additional allowed storage accounts
+var allStorageAccountNames = union([privateStorageAcctName], allowedStorageAccountNames)
+// Generate blob, dfs, and file endpoints for each storage account
+var storageAllowedDomains = flatten(map(allStorageAccountNames, name => [
+  '${name}.blob.${storageSuffix}'
+  '${name}.dfs.${storageSuffix}'
+  '${name}.file.${storageSuffix}'
+]))
+// Include the Key Vault used by the Key Vault linked service to retrieve connection strings
+var allowedDomains = concat(storageAllowedDomains, ['${keyVaultName}${keyVaultSuffix}'])
+
 resource privateStorageAcct 'Microsoft.Storage/storageAccounts@2021-08-01' existing = {
   name: privateStorageAcctName
 }
@@ -511,6 +528,25 @@ resource adfPrivateStgRole 'Microsoft.Authorization/roleAssignments@2022-04-01'
   }
 }
 
+// Assign the built-in Azure Policy to restrict ADF outbound access to allowed domains only.
+// This prevents data exfiltration by blocking pipeline communication with unapproved destinations.
+// Policy: "[Preview]: Azure Data Factory pipelines should only communicate with allowed domains"
+resource adfOutboundPolicyAssignment 'Microsoft.Authorization/policyAssignments@2022-06-01' = {
+  name: take(replace(baseName, '{rtype}', 'pa-adf-out'), 64)
+  scope: resourceGroup()
+  properties: {
+    policyDefinitionId: '/providers/Microsoft.Authorization/policyDefinitions/3d02a511-74e5-4dab-a5fd-878704d4a61a'
+    parameters: {
+      effect: {
+        value: 'Deny'
+      }
+      allowedDomainNames: {
+        value: allowedDomains
+      }
+    }
+  }
+}
+
 output principalId string = adf.identity.principalId
 output name string = adf.name
 

research-spoke/spoke-modules/airlock/main.bicep

@@ -250,12 +250,26 @@ module adfModule 'adf.bicep' = {
     usePrivateEndpoint: usePrivateEndpoints
     privateEndpointSubnetId: usePrivateEndpoints ? privateEndpointSubnetId : ''
     privateDnsZonesResourceGroupId: usePrivateEndpoints ? privateDnsZonesResourceGroupId : ''
+
+    // Storage accounts the ADF is allowed to access (for outbound access control policy)
+    allowedStorageAccountNames: [
+      publicStorageAccountNameModule.outputs.validName
+      airlockStorageAccountNameForPolicy
+    ]
   }
 }
 
 var airlockStorageAccountName = useCentralizedReview
   ? centralizedModule.outputs.centralAirlockStorageAccountName
   : spokeAirlockStorageAccountModule.outputs.storageAccountName
+
+// Derive the airlock storage account name without taking a dependency on centralizedModule
+// (which itself depends on adfModule, which would create a circular dependency).
+// For centralized review, extract the name from the resource ID parameter.
+// For non-centralized review, use the spoke airlock storage account module output.
+var airlockStorageAccountNameForPolicy = useCentralizedReview
+  ? last(split(centralAirlockResources.storageAccountId, '/'))
+  : spokeAirlockStorageAccountModule.outputs.storageAccountName
 var airlocKeyVaultUri = useCentralizedReview
   ? centralizedModule.outputs.centralKeyVaultUri
   : keyVault.properties.vaultUri