Microsoft Sentinel Analytic Rules
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S3 object publicly exposed

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Id09f2a28b-3286-4268-9e2f-33805f104e5d
RulenameS3 object publicly exposed
DescriptionDetected S3 bucket that’s publicly exposed, which could lead to sensitive information leakage to the public. Verify the S3 object configurations.
SeverityMedium
TacticsExfiltration
TechniquesT1537
Required data connectorsAWS
KindScheduled
Query frequency1h
Query period1h
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_S3ObjectPubliclyExposed.yaml
Version1.0.0
Arm template09f2a28b-3286-4268-9e2f-33805f104e5d.json
Deploy To Azure
AWSCloudTrail
  | where EventName == "PutObjectAcl" 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 object publicly exposed
id: 09f2a28b-3286-4268-9e2f-33805f104e5d
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_S3ObjectPubliclyExposed.yaml
severity: Medium
query: |
  AWSCloudTrail
    | where EventName == "PutObjectAcl" 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 that's publicly exposed, which could lead to 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/09f2a28b-3286-4268-9e2f-33805f104e5d')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/09f2a28b-3286-4268-9e2f-33805f104e5d')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01",
      "properties": {
        "displayName": "S3 object publicly exposed",
        "description": "'Detected S3 bucket that's publicly exposed, which could lead to sensitive information leakage to the public. Verify the S3 object configurations.'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "AWSCloudTrail\n  | where EventName == \"PutObjectAcl\" 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": "09f2a28b-3286-4268-9e2f-33805f104e5d",
        "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_S3ObjectPubliclyExposed.yaml",
        "status": "Available",
        "templateVersion": "1.0.0"
      }
    }
  ]
}