Tailscale Policy file ACL modified

Tailscale_Audit_CL
| where Action == "UPDATE"
| where tostring(Target.type) == "TAILNET"
| where tostring(Target.property) == "ACL"
| extend ActorLogin = tostring(Actor.loginName)
| project TimeGenerated, ActorLogin, Action, Target, Origin, Old, New

incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    lookbackDuration: PT5H
    reopenClosedIncident: false
    enabled: true
    matchingMethod: AllEntities
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: ActorLogin
    identifier: FullName
query: |
  Tailscale_Audit_CL
  | where Action == "UPDATE"
  | where tostring(Target.type) == "TAILNET"
  | where tostring(Target.property) == "ACL"
  | extend ActorLogin = tostring(Actor.loginName)
  | project TimeGenerated, ActorLogin, Action, Target, Origin, Old, New
id: 1e7249c2-1a9d-05fd-45cb-c859eef5b8ae
queryFrequency: 15m
status: Available
version: 1.0.0
severity: Medium
relevantTechniques:
- T1556
name: 'Tailscale: Policy file (ACL) modified'
kind: Scheduled
tactics:
- DefenseEvasion
- Persistence
requiredDataConnectors:
- dataTypes:
  - Tailscale_Audit_CL
  connectorId: TailscaleCCF
description: |
  Identifies when the tailnet ACL/policy file is modified. Review the diff - incorrect ACLs can silently expand blast radius across the tailnet.
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Tailscale%20%28CCF%29/Analytic%20Rules/TailscalePolicyfileACLmodified.yaml
triggerOperator: gt
triggerThreshold: 0
queryPeriod: 15m

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/1e7249c2-1a9d-05fd-45cb-c859eef5b8ae')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/1e7249c2-1a9d-05fd-45cb-c859eef5b8ae')]",
      "properties": {
        "alertRuleTemplateName": "1e7249c2-1a9d-05fd-45cb-c859eef5b8ae",
        "customDetails": null,
        "description": "Identifies when the tailnet ACL/policy file is modified. Review the diff - incorrect ACLs can silently expand blast radius across the tailnet.\n",
        "displayName": "Tailscale: Policy file (ACL) modified",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "ActorLogin",
                "identifier": "FullName"
              }
            ]
          }
        ],
        "incidentConfiguration": {
          "createIncident": true,
          "groupingConfiguration": {
            "enabled": true,
            "lookbackDuration": "PT5H",
            "matchingMethod": "AllEntities",
            "reopenClosedIncident": false
          }
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Tailscale%20%28CCF%29/Analytic%20Rules/TailscalePolicyfileACLmodified.yaml",
        "query": "Tailscale_Audit_CL\n| where Action == \"UPDATE\"\n| where tostring(Target.type) == \"TAILNET\"\n| where tostring(Target.property) == \"ACL\"\n| extend ActorLogin = tostring(Actor.loginName)\n| project TimeGenerated, ActorLogin, Action, Target, Origin, Old, New\n",
        "queryFrequency": "PT15M",
        "queryPeriod": "PT15M",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion",
          "Persistence"
        ],
        "techniques": [
          "T1556"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}