GCP IAM - Publicly exposed storage bucket

GCP_IAM
| where PayloadMethodname =~ 'google.iam.v1.IAMPolicy.SetIamPolicy'
| where ResourceType has 'bucket'
| extend members = parse_json(todynamic(PayloadRequestPolicyBindings))[0]['members']
| extend action = parse_json(todynamic(PayloadRequestPolicyBindings))[0]['action']
| where members in~ ('allUsers', 'allAuthenticatedUsers')
| where action =~ 'ADD'
| extend timestamp = TimeGenerated, AccountCustomEntity = PayloadAuthenticationinfoPrincipalemail, IPCustomEntity = SrcIpAddr

name: GCP IAM - Publicly exposed storage bucket
status: Available
triggerThreshold: 0
severity: Medium
tactics:
- Discovery
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/GoogleCloudPlatformIAM/Analytic Rules/GCPIAMPublicBucket.yaml
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: AccountCustomEntity
    identifier: FullName
- entityType: IP
  fieldMappings:
  - columnName: IPCustomEntity
    identifier: Address
queryPeriod: 1h
queryFrequency: 1h
version: 1.0.0
triggerOperator: gt
description: |
    'Detects possible misconfiguration for bucket policy making it publicly available.'
query: |
  GCP_IAM
  | where PayloadMethodname =~ 'google.iam.v1.IAMPolicy.SetIamPolicy'
  | where ResourceType has 'bucket'
  | extend members = parse_json(todynamic(PayloadRequestPolicyBindings))[0]['members']
  | extend action = parse_json(todynamic(PayloadRequestPolicyBindings))[0]['action']
  | where members in~ ('allUsers', 'allAuthenticatedUsers')
  | where action =~ 'ADD'
  | extend timestamp = TimeGenerated, AccountCustomEntity = PayloadAuthenticationinfoPrincipalemail, IPCustomEntity = SrcIpAddr  
relevantTechniques:
- T1069
id: 4a433846-4b05-4a27-99d7-92093feded79
requiredDataConnectors:
- dataTypes:
  - GCP_IAM
  connectorId: GCPIAMDataConnector
kind: Scheduled

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/4a433846-4b05-4a27-99d7-92093feded79')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/4a433846-4b05-4a27-99d7-92093feded79')]",
      "properties": {
        "alertRuleTemplateName": "4a433846-4b05-4a27-99d7-92093feded79",
        "customDetails": null,
        "description": "'Detects possible misconfiguration for bucket policy making it publicly available.'\n",
        "displayName": "GCP IAM - Publicly exposed storage bucket",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "FullName"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "IPCustomEntity",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/GoogleCloudPlatformIAM/Analytic Rules/GCPIAMPublicBucket.yaml",
        "query": "GCP_IAM\n| where PayloadMethodname =~ 'google.iam.v1.IAMPolicy.SetIamPolicy'\n| where ResourceType has 'bucket'\n| extend members = parse_json(todynamic(PayloadRequestPolicyBindings))[0]['members']\n| extend action = parse_json(todynamic(PayloadRequestPolicyBindings))[0]['action']\n| where members in~ ('allUsers', 'allAuthenticatedUsers')\n| where action =~ 'ADD'\n| extend timestamp = TimeGenerated, AccountCustomEntity = PayloadAuthenticationinfoPrincipalemail, IPCustomEntity = SrcIpAddr\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Discovery"
        ],
        "techniques": [
          "T1069"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}