Microsoft Sentinel Analytic Rules
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GCP IAM - Publicly exposed storage bucket

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Id4a433846-4b05-4a27-99d7-92093feded79
RulenameGCP IAM - Publicly exposed storage bucket
DescriptionDetects possible misconfiguration for bucket policy making it publicly available.
SeverityMedium
TacticsDiscovery
TechniquesT1069
Required data connectorsGCPIAMDataConnector
KindScheduled
Query frequency1h
Query period1h
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Solutions/GoogleCloudPlatformIAM/Analytic Rules/GCPIAMPublicBucket.yaml
Version1.0.1
Arm template4a433846-4b05-4a27-99d7-92093feded79.json
Deploy To Azure
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 AccountName = tostring(split(PayloadAuthenticationinfoPrincipalemail, "@")[0]), AccountUPNSuffix = tostring(split(PayloadAuthenticationinfoPrincipalemail, "@")[1])
tactics:
- Discovery
entityMappings:
- fieldMappings:
  - columnName: PayloadAuthenticationinfoPrincipalemail
    identifier: FullName
  - columnName: AccountName
    identifier: Name
  - columnName: AccountUPNSuffix
    identifier: UPNSuffix
  entityType: Account
- fieldMappings:
  - columnName: SrcIpAddr
    identifier: Address
  entityType: IP
queryPeriod: 1h
requiredDataConnectors:
- dataTypes:
  - GCP_IAM
  connectorId: GCPIAMDataConnector
triggerThreshold: 0
status: Available
kind: Scheduled
relevantTechniques:
- T1069
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/GoogleCloudPlatformIAM/Analytic Rules/GCPIAMPublicBucket.yaml
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 AccountName = tostring(split(PayloadAuthenticationinfoPrincipalemail, "@")[0]), AccountUPNSuffix = tostring(split(PayloadAuthenticationinfoPrincipalemail, "@")[1])  
version: 1.0.1
id: 4a433846-4b05-4a27-99d7-92093feded79
name: GCP IAM - Publicly exposed storage bucket
queryFrequency: 1h
triggerOperator: gt
severity: Medium
{
  "$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/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": "PayloadAuthenticationinfoPrincipalemail",
                "identifier": "FullName"
              },
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "AccountUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SrcIpAddr",
                "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 AccountName = tostring(split(PayloadAuthenticationinfoPrincipalemail, \"@\")[0]), AccountUPNSuffix = tostring(split(PayloadAuthenticationinfoPrincipalemail, \"@\")[1])\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Discovery"
        ],
        "techniques": [
          "T1069"
        ],
        "templateVersion": "1.0.1",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}