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 Console

Login to Azure Monitor console
Select Alerts
Click On New Alert Rule
Under Scope, click Select resource
Select the appropriate subscription under Filter by subscription
Select Policy Assignment under Filter by resource type
Select All for Filter by location
Click on the subscription resource from the entries populated under Resource
Verify Selection preview shows All Policy assignment (policyAssignments) and your selected subscription name
Click Done
Under Condition section click Add Condition
Select Delete Network Security Group signal
Click Done
Under Action group in Actions section, select Add action groups and complete creation process or select appropriate action group
Under Alert rule details, enter Alert rule name and Description
Select appropriate resource group to save the alert to
Check Enable alert rule upon creation checkbox
Click Create alert rule

From Command Line

Use the below command to create an Activity Log Alert for Create or Update Network Security Groups

az account get-access-token --query "{subscription:subscription,accessToken:accessToken}" \
--out tsv | xargs -L1 bash -c 'curl -X PUT -H "Authorization: Bearer $1" -H \
"Content-Type:application/json" \
https://management.azure.com/subscriptions/$0/resourceGroups/<Resource_Group_ToCreate_Alert_In>/providers/microsoft.insights/activityLogAlerts/<Unique_Alert_Name>?api-version=2017-04-01 -d@"input.json"'

Where input.json contains the Request body JSON data as mentioned below.

{
  "location":"Global",
  "tags":{

  },
  "properties":{
     "scopes":[
        "/subscriptions/<Subscription_ID>"
     ],
     "enabled":true,
     "condition":{
        "allOf":[
           {
              "containsAny":null,
              "equals":"Administrative",
              "field":"category"
           },
           {
              "containsAny":null,
              "equals":"Microsoft.Network/networkSecurityGroups/delete",
              "field":"operationName"
           }
        ]
     },
     "actions":{
        "actionGroups":[
           {
              "actionGroupId":"/subscriptions/<Subscription_ID>/resourceGroups/<Resource_Group_For_Alert_Group>/providers/microsoft.insights/actionGroups/<Alert_Group>",
              "webhookProperties":null
           }
        ]
     }
  }
}

Configurable Parameters for command line:

<Resource_Group_To Create_Alert_In> <Unique_Alert_Name>

Configurable Parameters for input.json:

<Subscription_ID> in scopes
<Subscription_ID> in actionGroupId
<Resource_Group_For_Alert_Group> in actionGroupId
<Alert_Group> in actionGroupId

Usage

Run the control in your terminal:

powerpipe control run azure_compliance.control.cis_v140_5_2_4

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run azure_compliance.control.cis_v140_5_2_4 --share

SQL

This control uses a named query:

with alert_rule as (
  select
    alert.id as alert_id,
    alert.name as alert_name,
    alert.enabled,
    alert.location,
    alert.subscription_id,
    jsonb_array_length(alert.condition -> 'allOf')
  from
    azure_log_alert as alert,
    jsonb_array_elements_text(scopes) as sc
  where
    alert.location = 'global'
    and alert.enabled
    and sc = '/subscriptions/' || alert.subscription_id
    and (
      (
        alert.condition -> 'allOf' @> '[{"equals":"Administrative","field":"category"}]'
        and alert.condition -> 'allOf' @> '[{"field": "operationName", "equals": "Microsoft.Network/networkSecurityGroups/delete"}]'
      )
      or
      (
        alert.condition -> 'allOf' @> '[{"equals":"Administrative","field":"category"}]'
        and alert.condition -> 'allOf' @> '[{"field": "resourceType", "equals": "microsoft.network/networksecuritygroups"}]'
        and jsonb_array_length(alert.condition -> 'allOf') = 2
      )
    )
  limit 1
)
  select
    sub.subscription_id as resource,
    case
      when count(a.subscription_id) > 0 then 'ok'
      else 'alarm'
    end as status,
    case
      when count(a.subscription_id) > 0 then 'Activity log alert exists for delete Network Security Group event.'
      else 'Activity log alert does not exists for delete Network Security Group event.'
    end as reason
    
    , sub.display_name as subscription
  from
    azure_subscription sub
    left join alert_rule a on sub.subscription_id = a.subscription_id
  group by
    sub._ctx,
    sub.subscription_id,
    sub.display_name;