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Analytic rule catalog

AWSCloudTrail - S3 bucket access point publicly exposed

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Idb7a44e0d-ae4c-4fb2-be1b-aa0e45f2327b
RulenameAWSCloudTrail - S3 bucket access point publicly exposed
DescriptionDetects S3 access point policy changes that allow public principals. Public exposure through access point

configuration can lead to unauthorized data access and potential information disclosure.
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%20Web%20Services/Analytic%20Rules/AWS_S3BucketAccessPointExposed.yaml
Version1.0.2
Arm templateb7a44e0d-ae4c-4fb2-be1b-aa0e45f2327b.json
Deploy To Azure
AWSCloudTrail
| where EventName == "PutAccessPointPolicy" and isempty(ErrorCode) and isempty(ErrorMessage)
| extend Statement = parse_json(tostring((parse_json(RequestParameters).PutAccessPointPolicyRequest.Policy))).Statement
| mvexpand Statement
| extend Action = parse_json(Statement).Action , Effect = tostring(parse_json(Statement).Effect), Resource = tostring(parse_json(Statement).Resource), Condition = tostring(parse_json(Statement).Condition), Principal_aws = tostring(parse_json(Statement).Principal.AWS), Principal = tostring(parse_json(Statement).Principal)
| extend Action = tostring(Action)
| where Effect =~ "Allow" and (Principal_aws == "*" or Principal == "*") and isempty(Condition)
| 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]), "")
| distinct TimeGenerated, EventName, SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityArn, UserIdentityUserName

name: AWSCloudTrail - S3 bucket access point publicly exposed
triggerOperator: gt
query: |
  AWSCloudTrail
  | where EventName == "PutAccessPointPolicy" and isempty(ErrorCode) and isempty(ErrorMessage)
  | extend Statement = parse_json(tostring((parse_json(RequestParameters).PutAccessPointPolicyRequest.Policy))).Statement
  | mvexpand Statement
  | extend Action = parse_json(Statement).Action , Effect = tostring(parse_json(Statement).Effect), Resource = tostring(parse_json(Statement).Resource), Condition = tostring(parse_json(Statement).Condition), Principal_aws = tostring(parse_json(Statement).Principal.AWS), Principal = tostring(parse_json(Statement).Principal)
  | extend Action = tostring(Action)
  | where Effect =~ "Allow" and (Principal_aws == "*" or Principal == "*") and isempty(Condition)
  | 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]), "")
  | distinct TimeGenerated, EventName, SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityArn, UserIdentityUserName
queryFrequency: 1h
description: |
  Detects S3 access point policy changes that allow public principals. Public exposure through access point
  configuration can lead to unauthorized data access and potential information disclosure.
id: b7a44e0d-ae4c-4fb2-be1b-aa0e45f2327b
triggerThreshold: 0
queryPeriod: 1h
version: 1.0.2
kind: Scheduled
customDetails:
  RecipientAccountId: RecipientAccountId
  EventName: EventName
  UserIdentityArn: UserIdentityArn
status: Available
severity: Medium
requiredDataConnectors:
- connectorId: AWS
  dataTypes:
  - AWSCloudTrail
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon%20Web%20Services/Analytic%20Rules/AWS_S3BucketAccessPointExposed.yaml
alertDetailsOverride:
  alertDescriptionFormat: Detected {{EventName}} from {{SourceIpAddress}} creating public S3 access point exposure in account {{RecipientAccountId}}.
  alertDisplayNameFormat: AWS S3 access point publicly exposed by {{AccountName}}
relevantTechniques:
- T1537
tactics:
- Exfiltration
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: AccountUPNSuffix
  - identifier: CloudAppAccountId
    columnName: RecipientAccountId
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: SourceIpAddress
  entityType: IP

{
  "$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/b7a44e0d-ae4c-4fb2-be1b-aa0e45f2327b')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/b7a44e0d-ae4c-4fb2-be1b-aa0e45f2327b')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "Detected {{EventName}} from {{SourceIpAddress}} creating public S3 access point exposure in account {{RecipientAccountId}}.",
          "alertDisplayNameFormat": "AWS S3 access point publicly exposed by {{AccountName}}"
        },
        "alertRuleTemplateName": "b7a44e0d-ae4c-4fb2-be1b-aa0e45f2327b",
        "customDetails": {
          "EventName": "EventName",
          "RecipientAccountId": "RecipientAccountId",
          "UserIdentityArn": "UserIdentityArn"
        },
        "description": "Detects S3 access point policy changes that allow public principals. Public exposure through access point\nconfiguration can lead to unauthorized data access and potential information disclosure.\n",
        "displayName": "AWSCloudTrail - S3 bucket access point 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%20Web%20Services/Analytic%20Rules/AWS_S3BucketAccessPointExposed.yaml",
        "query": "AWSCloudTrail\n| where EventName == \"PutAccessPointPolicy\" and isempty(ErrorCode) and isempty(ErrorMessage)\n| extend Statement = parse_json(tostring((parse_json(RequestParameters).PutAccessPointPolicyRequest.Policy))).Statement\n| mvexpand Statement\n| extend Action = parse_json(Statement).Action , Effect = tostring(parse_json(Statement).Effect), Resource = tostring(parse_json(Statement).Resource), Condition = tostring(parse_json(Statement).Condition), Principal_aws = tostring(parse_json(Statement).Principal.AWS), Principal = tostring(parse_json(Statement).Principal)\n| extend Action = tostring(Action)\n| where Effect =~ \"Allow\" and (Principal_aws == \"*\" or Principal == \"*\") and isempty(Condition)\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| distinct TimeGenerated, EventName, SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityArn, UserIdentityUserName\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Exfiltration"
        ],
        "techniques": [
          "T1537"
        ],
        "templateVersion": "1.0.2",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}