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])
name: GCP IAM - Publicly exposed storage bucket
tactics:
- Discovery
kind: Scheduled
description: |
    'Detects possible misconfiguration for bucket policy making it publicly available.'
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
version: 1.0.1
triggerThreshold: 0
queryFrequency: 1h
triggerOperator: gt
relevantTechniques:
- T1069
requiredDataConnectors:
- connectorId: GCPIAMDataConnector
  dataTypes:
  - GCP_IAM
severity: Medium
queryPeriod: 1h
status: 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])  
id: 4a433846-4b05-4a27-99d7-92093feded79
{
  "$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"
    }
  ]
}