Modify-NSG.json

{
    "name": "Modify-NSG",
    "type": "Microsoft.Authorization/policyDefinitions",
    "apiVersion": "2021-06-01",
    "scope": null,
    "properties": {
        "policyType": "Custom",
        "mode": "All",
        "displayName": "Enforce specific configuration of Network Security Groups (NSG)",
        "description": "This policy enforces the configuration of Network Security Groups (NSG).",
        "metadata": {
            "version": "1.0.0",
            "category": "Network",
            "source": "https://github.com/Azure/Enterprise-Scale/",
            "alzCloudEnvironments": [
                "AzureCloud",
                "AzureChinaCloud",
                "AzureUSGovernment"
            ]
        },
        "parameters": {
            "effect": {
                "type": "String",
                "allowedValues": [
                    "Modify",
                    "Disabled"
                ],
                "defaultValue": "Modify",
                "metadata": {
                    "displayName": "Effect",
                    "description": "Enable or disable the execution of the policy"
                }
            },
            "nsgRuleName": {
                "type": "string",
                "defaultValue": "DenyAnyInternetOutbound"
            },
            "nsgRulePriority": {
                "type": "integer",
                "defaultValue": 1000
            },
            "nsgRuleDirection": {
                "type": "string",
                "allowedValues": [
                    "Inbound",
                    "Outbound"
                ],
                "defaultValue": "Outbound"
            },
            "nsgRuleAccess": {
                "type": "string",
                "allowedValues": [
                    "Allow",
                    "Deny"
                ],
                "defaultValue": "Deny"
            },
            "nsgRuleProtocol": {
                "type": "string",
                "defaultValue": "*"
            },
            "nsgRuleSourceAddressPrefix": {
                "type": "string",
                "defaultValue": "*"
            },
            "nsgRuleSourcePortRange": {
                "type": "string",
                "defaultValue": "*"
            },
            "nsgRuleDestinationAddressPrefix": {
                "type": "string",
                "defaultValue": "Internet"
            },
            "nsgRuleDestinationPortRange": {
                "type": "string",
                "defaultValue": "*"
            },
            "nsgRuleDescription": {
                "type": "string",
                "defaultValue": "Deny any outbound traffic to the Internet"
            }
        },
        "policyRule": {
            "if": {
                "allOf": [
                    {
                        "field": "type",
                        "equals": "Microsoft.Network/networkSecurityGroups"
                    },
                    {
                        "count": {
                            "field": "Microsoft.Network/networkSecurityGroups/securityRules[*]"
                        },
                        "equals": 0
                    }
                ]
            },
            "then": {
                "effect": "[[parameters('effect')]",
                "details": {
                    "roleDefinitionIds": [
                        "/providers/microsoft.authorization/roleDefinitions/4d97b98b-1d4f-4787-a291-c67834d212e7"
                    ],
                    "conflictEffect": "audit",
                    "operations": [
                        {
                            "operation": "add",
                            "field": "Microsoft.Network/networkSecurityGroups/securityRules[*]",
                            "value": {
                                "name": "[[parameters('nsgRuleName')]",
                                "properties": {
                                    "description": "[[parameters('nsgRuleDescription')]",
                                    "protocol": "[[parameters('nsgRuleProtocol')]",
                                    "sourcePortRange": "[[parameters('nsgRuleSourcePortRange')]",
                                    "destinationPortRange": "[[parameters('nsgRuleDestinationPortRange')]",
                                    "sourceAddressPrefix": "[[parameters('nsgRuleSourceAddressPrefix')]",
                                    "destinationAddressPrefix": "[[parameters('nsgRuleDestinationAddressPrefix')]",
                                    "access": "[[parameters('nsgRuleAccess')]",
                                    "priority": "[[parameters('nsgRulePriority')]",
                                    "direction": "[[parameters('nsgRuleDirection')]"
                                }
                            }
                        }
                    ]
                }
            }
        }
    }
}