S3 bucket exposed via ACL

AWSCloudTrail
| where EventName == "PutBucketAcl" and isempty(ErrorCode) and isempty(ErrorMessage)
| extend Grant = parse_json(tostring((parse_json(RequestParameters).AccessControlPolicy))).AccessControlList.Grant
| mvexpand Grant
| extend cannedacl = parse_json(tostring((parse_json(RequestParameters))))
| extend URI = parse_json(Grant).Grantee.URI, type = parse_json(Grant).Grantee.["xsi:type"], xamzacl = parse_json(cannedacl).["x-amz-acl"]
| where (type == "Group" and (URI endswith "AllUsers" or URI endswith "AuthenticatedUsers"))
  or xamzacl in ("authenticated-read","public-read","public-read-write")
| extend UserIdentityUserName = iff(isnotempty(UserIdentityUserName), UserIdentityUserName, tostring(split(UserIdentityArn,'/')[-1]))
| extend timestamp = TimeGenerated, IPCustomEntity = SourceIpAddress, AccountCustomEntity = UserIdentityUserName

queryPeriod: 1h
version: 1.0.0
relevantTechniques:
- T1537
queryFrequency: 1h
kind: Scheduled
name: S3 bucket exposed via ACL
id: 6b9b4ee6-f4c1-4b86-8c8c-beb0bb59ae44
entityMappings:
- fieldMappings:
  - columnName: AccountCustomEntity
    identifier: FullName
  entityType: Account
- fieldMappings:
  - columnName: IPCustomEntity
    identifier: Address
  entityType: IP
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_S3BucketExposedviaACL.yaml
severity: Medium
query: |
  AWSCloudTrail
  | where EventName == "PutBucketAcl" and isempty(ErrorCode) and isempty(ErrorMessage)
  | extend Grant = parse_json(tostring((parse_json(RequestParameters).AccessControlPolicy))).AccessControlList.Grant
  | mvexpand Grant
  | extend cannedacl = parse_json(tostring((parse_json(RequestParameters))))
  | extend URI = parse_json(Grant).Grantee.URI, type = parse_json(Grant).Grantee.["xsi:type"], xamzacl = parse_json(cannedacl).["x-amz-acl"]
  | where (type == "Group" and (URI endswith "AllUsers" or URI endswith "AuthenticatedUsers"))
    or xamzacl in ("authenticated-read","public-read","public-read-write")
  | extend UserIdentityUserName = iff(isnotempty(UserIdentityUserName), UserIdentityUserName, tostring(split(UserIdentityArn,'/')[-1]))
  | extend timestamp = TimeGenerated, IPCustomEntity = SourceIpAddress, AccountCustomEntity = UserIdentityUserName  
tactics:
- Exfiltration
description: |
    'Detected S3 bucket publicly exposed via ACL, which could lead for sensitive information leakage to the public. Verify the S3 object configurations.'
requiredDataConnectors:
- connectorId: AWS
  dataTypes:
  - AWSCloudTrail
status: Available
triggerThreshold: 0
triggerOperator: gt

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/6b9b4ee6-f4c1-4b86-8c8c-beb0bb59ae44')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/6b9b4ee6-f4c1-4b86-8c8c-beb0bb59ae44')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01",
      "properties": {
        "displayName": "S3 bucket exposed via ACL",
        "description": "'Detected S3 bucket publicly exposed via ACL, which could lead for sensitive information leakage to the public. Verify the S3 object configurations.'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "AWSCloudTrail\n| where EventName == \"PutBucketAcl\" and isempty(ErrorCode) and isempty(ErrorMessage)\n| extend Grant = parse_json(tostring((parse_json(RequestParameters).AccessControlPolicy))).AccessControlList.Grant\n| mvexpand Grant\n| extend cannedacl = parse_json(tostring((parse_json(RequestParameters))))\n| extend URI = parse_json(Grant).Grantee.URI, type = parse_json(Grant).Grantee.[\"xsi:type\"], xamzacl = parse_json(cannedacl).[\"x-amz-acl\"]\n| where (type == \"Group\" and (URI endswith \"AllUsers\" or URI endswith \"AuthenticatedUsers\"))\n  or xamzacl in (\"authenticated-read\",\"public-read\",\"public-read-write\")\n| extend UserIdentityUserName = iff(isnotempty(UserIdentityUserName), UserIdentityUserName, tostring(split(UserIdentityArn,'/')[-1]))\n| extend timestamp = TimeGenerated, IPCustomEntity = SourceIpAddress, AccountCustomEntity = UserIdentityUserName\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Exfiltration"
        ],
        "techniques": [
          "T1537"
        ],
        "alertRuleTemplateName": "6b9b4ee6-f4c1-4b86-8c8c-beb0bb59ae44",
        "customDetails": null,
        "entityMappings": [
          {
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "AccountCustomEntity"
              }
            ],
            "entityType": "Account"
          },
          {
            "fieldMappings": [
              {
                "identifier": "Address",
                "columnName": "IPCustomEntity"
              }
            ],
            "entityType": "IP"
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_S3BucketExposedviaACL.yaml",
        "status": "Available",
        "templateVersion": "1.0.0"
      }
    }
  ]
}