Microsoft Sentinel Analytic Rules
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S3 bucket exposed via policy

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Id44a5b65e-b0a9-4591-aabc-388fd92a28c4
RulenameS3 bucket exposed via policy
DescriptionDetected S3 bucket publicly exposed via policy, this could lead for 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_S3BucketExposedviaPolicy.yaml
Version1.0.1
Arm template44a5b65e-b0a9-4591-aabc-388fd92a28c4.json
Deploy To Azure
AWSCloudTrail
| where EventName == "PutBucketPolicy" and isempty(ErrorCode) and isempty(ErrorMessage)
| extend Statement = parse_json(tostring((parse_json(RequestParameters).bucketPolicy))).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
| extend timestamp = TimeGenerated
id: 44a5b65e-b0a9-4591-aabc-388fd92a28c4
triggerOperator: gt
status: Available
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: AccountUPNSuffix
  - identifier: CloudAppAccountId
    columnName: RecipientAccountId
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: SourceIpAddress
  entityType: IP
description: |
    'Detected S3 bucket publicly exposed via policy, this could lead for sensitive information leakage to the public. Verify the S3 object configurations.'
severity: Medium
version: 1.0.1
relevantTechniques:
- T1537
tactics:
- Exfiltration
name: S3 bucket exposed via policy
queryFrequency: 1h
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon Web Services/Analytic Rules/AWS_S3BucketExposedviaPolicy.yaml
query: |
  AWSCloudTrail
  | where EventName == "PutBucketPolicy" and isempty(ErrorCode) and isempty(ErrorMessage)
  | extend Statement = parse_json(tostring((parse_json(RequestParameters).bucketPolicy))).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
  | extend timestamp = TimeGenerated  
kind: Scheduled
triggerThreshold: 0
requiredDataConnectors:
- dataTypes:
  - AWSCloudTrail
  connectorId: AWS
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/44a5b65e-b0a9-4591-aabc-388fd92a28c4')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/44a5b65e-b0a9-4591-aabc-388fd92a28c4')]",
      "properties": {
        "alertRuleTemplateName": "44a5b65e-b0a9-4591-aabc-388fd92a28c4",
        "customDetails": null,
        "description": "'Detected S3 bucket publicly exposed via policy, this could lead for sensitive information leakage to the public. Verify the S3 object configurations.'\n",
        "displayName": "S3 bucket exposed via policy",
        "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_S3BucketExposedviaPolicy.yaml",
        "query": "AWSCloudTrail\n| where EventName == \"PutBucketPolicy\" and isempty(ErrorCode) and isempty(ErrorMessage)\n| extend Statement = parse_json(tostring((parse_json(RequestParameters).bucketPolicy))).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| 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"
    }
  ]
}