Deny-Storage-ResourceAccessRulesResourceId.json

{
    "name": "Deny-Storage-ResourceAccessRulesResourceId",
    "type": "Microsoft.Authorization/policyDefinitions",
    "apiVersion": "2021-06-01",
    "scope": null,
    "properties": {
        "policyType": "Custom",
        "mode": "All",
        "displayName": "Resource Access Rules resource IDs should be restricted for Storage Accounts",
        "description": "Azure Storage accounts should restrict the resource access rule for service-level network ACLs to services from a specific Azure subscription. Enforce this for increased data exfiltration protection.",
        "metadata": {
            "version": "1.0.0",
            "category": "Storage",
            "source": "https://github.com/Azure/Enterprise-Scale/",
            "alzCloudEnvironments": [
                "AzureCloud",
                "AzureChinaCloud",
                "AzureUSGovernment"
            ]
        },
        "parameters": {
            "effect": {
                "type": "String",
                "allowedValues": [
                    "Audit",
                    "Deny",
                    "Disabled"
                ],
                "defaultValue": "Deny",
                "metadata": {
                    "displayName": "Effect",
                    "description": "Enable or disable the execution of the policy"
                }
            }
        },
        "policyRule": {
            "if": {
                "allOf": [
                    {
                        "field": "type",
                        "equals": "Microsoft.Storage/storageAccounts"
                    },
                    {
                        "count": {
                            "field": "Microsoft.Storage/storageAccounts/networkAcls.resourceAccessRules[*]"
                        },
                        "greater": 0
                    },
                    {
                        "count": {
                            "field": "Microsoft.Storage/storageAccounts/networkAcls.resourceAccessRules[*]",
                            "where": {
                                "value": "[[split(current('Microsoft.Storage/storageAccounts/networkAcls.resourceAccessRules[*].resourceId'), '/')[2]]",
                                "equals": "*"
                            }
                        },
                        "greater": 0
                    }
                ]
            },
            "then": {
                "effect": "[[parameters('effect')]"
            }
        }
    }
}