Control: 5.2.4 Ensure that Activity Log Alert exists for Delete Network Security Group

Description

Create an activity log alert for the Delete Network Security Group event.

Monitoring for "Delete Network Security Group" events gives insight into network access changes and may reduce the time it takes to detect suspicious activity.

Remediation

From Azure Portal

1. Navigate to the Monitor blade.
2. Select Alerts.
3. Select Create.
4. Select Alert rule.
5. Under Filter by subscription, choose a subscription.
6. Under Filter by resource type, select Network security groups.
7. Under Filter by location, select All.
8. From the results, select the subscription.
9. Select Done.
10. Select the Condition tab.
11. Under Signal name, click Delete Network Security Group (Microsoft.Network/networkSecurityGroups).
12. Select the Actions tab.
13. To use an existing action group, click Select action groups. To create a new action group, click Create action group. Fill out the appropriate details for the selection.
14. Select the Details tab.
15. Select a Resource group, provide an Alert rule name and an optional Alert rule description.
16. Click Review + create.
17. Click Create.

From Azure CLI

az monitor activity-log alert create --resource-group "<resource group name>" --condition category=Administrative and operationName=Microsoft.Network/networkSecurityGroups/delete and level=<verbose | information | warning | error | critical>--scope "/subscriptions/<subscription ID>" --name "<activity log rule name>" -- subscription <subscription id> --action-group <action group ID> --location global

From PowerShell

Create the Conditions object.

$conditions = @()
$conditions += New-AzActivityLogAlertAlertRuleAnyOfOrLeafConditionObject - Equal Administrative -Field category
$conditions += New-AzActivityLogAlertAlertRuleAnyOfOrLeafConditionObject - Equal Microsoft.Network/networkSecurityGroups/delete -Field operationName $conditions += New-AzActivityLogAlertAlertRuleAnyOfOrLeafConditionObject - Equal Verbose -Field level

Retrieve the Action Group information and store in a variable, then create the Actions object.

$actionGroup = Get-AzActionGroup -ResourceGroupName <resource group name> - Name <action group name>
$actionObject = New-AzActivityLogAlertActionGroupObject -Id $actionGroup.Id

Create the Scope object

$scope = "/subscriptions/<subscription id>"

Create the Activity Log Alert Rule for Microsoft.Network/networkSecurityGroups/delete

New-AzActivityLogAlert -Name "<activity log alert rule name>" -
ResourceGroupName "<resource group name>" -Condition $conditions -Scope $scope -Location global -Action $actionObject -Subscription <subscription ID> -Enabled $true

Default Value

By default, no monitoring alerts are created.