azure-policy-assignment-delete-unalerted: Azure Policy Assignment Delete Alert Not Configured

id: azure-policy-assignment-delete-unalerted
info:
  name: Azure Policy Assignment Delete Alert Not Configured
  author: princechaddha
  severity: high
  description: |
    Ensure that an Azure activity log alert is used to detect "Delete Policy Assignment" events within your Microsoft Azure cloud account. Activity log alerts get activated when a new activity log event that matches the condition specified in the alert occurs. In this case, the condition used is 'Whenever the Policy Activity Log "Delete policy assignment (policyAssignments)" has "any" level, with "any" status and event is initiated by "any"'.
  impact: |
    Failing to monitor "Delete Policy Assignment" events can lead to unauthorized policy changes that could affect resource compliance and security without notice.
  remediation: |
    Configure alert rules to monitor and notify on "Delete Policy Assignment" events by setting the alert condition to "Microsoft.Authorization/policyAssignments/delete" and ensuring that an action group is attached for notifications.
  reference:
    - https://docs.microsoft.com/en-us/azure/azure-monitor/platform/alerts-activity-log
  tags: cloud,devops,azure,microsoft,policy-assignment,azure-cloud-config

flow: |
  code(1);
  for (let AlertData of iterate(template.alertList)) {
    set("id", AlertData);
    code(2);
  }

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      az monitor activity-log alert list --output json --query '[?(enabled==`true`)].id'

    extractors:
      - type: json
        name: alertList
        internal: true
        json:
          - '.[]'

  - engine:
      - sh
      - bash
    source: |
      az monitor activity-log alert show --ids "$id" --query 'condition'

    matchers-condition: and
    matchers:
      - type: word
        words:
          - '"field": "operationName"'

      - type: word
        words:
          - "Microsoft.Authorization/policyAssignments/delete"
        negative: true

    extractors:
      - type: dsl
        dsl:
          - 'id + " does not have the correct alert configuration for Delete Policy Assignment events"'
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