Control: 5.2.2 Ensure that Activity Log Alert exists for Delete Policy Assignment

Description

Create an activity log alert for the Create Policy Assignment event.

Monitoring for create policy assignment events gives insight into changes done in "azure policy - assignments" and can reduce the time it takes to detect unsolicited changes. By default, no monitoring alerts are created.

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 Create policy assignment under signal name
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 policy assignment

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.Authorization/policyAssignments/write",
               "field":"operationName"
            }
         ]
      },
      "actions":{
         "actionGroups":[
            {
               "actionGroupId":"/subscriptions/<Subscription_ID>/resourceGroups/<Resource_Group_For_Alert_Gr
oup>/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_2

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run azure_compliance.control.cis_v140_5_2_2 --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
  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.Authorization/policyAssignments/delete"}]'
  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 policy assignment event.'
    else 'Activity log alert does not exists for delete policy assignment 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;