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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

queryFrequency: 1h
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
version: 1.0.2
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: AccountName
    identifier: Name
  - columnName: AccountUPNSuffix
    identifier: UPNSuffix
  - columnName: RecipientAccountId
    identifier: CloudAppAccountId
- entityType: IP
  fieldMappings:
  - columnName: SourceIpAddress
    identifier: Address
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.
kind: Scheduled
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon%20Web%20Services/Analytic%20Rules/AWS_S3BucketAccessPointExposed.yaml
triggerThreshold: 0
id: b7a44e0d-ae4c-4fb2-be1b-aa0e45f2327b
customDetails:
  RecipientAccountId: RecipientAccountId
  EventName: EventName
  UserIdentityArn: UserIdentityArn
alertDetailsOverride:
  alertDisplayNameFormat: AWS S3 access point publicly exposed by {{AccountName}}
  alertDescriptionFormat: Detected {{EventName}} from {{SourceIpAddress}} creating public S3 access point exposure in account {{RecipientAccountId}}.
severity: Medium
status: Available
relevantTechniques:
- T1537
requiredDataConnectors:
- connectorId: AWS
  dataTypes:
  - AWSCloudTrail
name: AWSCloudTrail - S3 bucket access point publicly exposed
tactics:
- Exfiltration
queryPeriod: 1h

{
  "$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"
    }
  ]
}