S3 object publicly exposed

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Id	09f2a28b-3286-4268-9e2f-33805f104e5d
Rulename	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.
Severity	Medium
Tactics	Exfiltration
Techniques	T1537
Required data connectors	AWS
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_S3ObjectPubliclyExposed.yaml
Version	1.0.1
Arm template	09f2a28b-3286-4268-9e2f-33805f104e5d.json

KQL

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 UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
  | extend UserName = tostring(split(UserIdentityArn, '/')[-1])
  | extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
  | extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
    AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "")
  | extend timestamp = TimeGenerated

YAML

relevantTechniques:
- T1537
name: S3 object publicly exposed
requiredDataConnectors:
- dataTypes:
  - AWSCloudTrail
  connectorId: AWS
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: AccountUPNSuffix
  - identifier: CloudAppAccountId
    columnName: RecipientAccountId
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: SourceIpAddress
  entityType: IP
triggerThreshold: 0
id: 09f2a28b-3286-4268-9e2f-33805f104e5d
tactics:
- Exfiltration
version: 1.0.1
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_S3ObjectPubliclyExposed.yaml
queryPeriod: 1h
kind: Scheduled
queryFrequency: 1h
severity: Medium
status: Available
description: |
    'Detected S3 bucket that's publicly exposed, which could lead to sensitive information leakage to the public. Verify the S3 object configurations.'
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 UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
    | extend UserName = tostring(split(UserIdentityArn, '/')[-1])
    | extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
    | extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
      AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "")
    | extend timestamp = TimeGenerated  
triggerOperator: gt

ARM

{
  "$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/09f2a28b-3286-4268-9e2f-33805f104e5d')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/09f2a28b-3286-4268-9e2f-33805f104e5d')]",
      "properties": {
        "alertRuleTemplateName": "09f2a28b-3286-4268-9e2f-33805f104e5d",
        "customDetails": null,
        "description": "'Detected S3 bucket that's publicly exposed, which could lead to sensitive information leakage to the public. Verify the S3 object configurations.'\n",
        "displayName": "S3 object publicly exposed",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "AccountUPNSuffix",
                "identifier": "UPNSuffix"
              },
              {
                "columnName": "RecipientAccountId",
                "identifier": "CloudAppAccountId"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SourceIpAddress",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_S3ObjectPubliclyExposed.yaml",
        "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 UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)\n  | extend UserName = tostring(split(UserIdentityArn, '/')[-1])\n  | extend AccountName = case( UserIdentityPrincipalid == \"Anonymous\", \"Anonymous\", isempty(UserIdentityUserName), UserName, UserIdentityUserName)\n  | extend AccountName = iif(AccountName contains \"@\", tostring(split(AccountName, '@', 0)[0]), AccountName),\n    AccountUPNSuffix = iif(AccountName contains \"@\", tostring(split(AccountName, '@', 1)[0]), \"\")\n  | extend timestamp = TimeGenerated\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Exfiltration"
        ],
        "techniques": [
          "T1537"
        ],
        "templateVersion": "1.0.1",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}