Trend Micro CAS - Unexpected file via mail

let f_types = dynamic(['ps1', 'bat', 'scr', 'sh', 'exe', 'js', 'lnk']);
TrendMicroCAS
| where EventCategoryType in~ ('exchange', 'gmail', 'exchangeserver')
| where isnotempty(SrcFileName)
| extend file_type = extract(@'\.(\w+)$', 1, SrcFileName)
| where file_type in~ (f_types)
| extend AccountCustomEntity = DstUserName

relevantTechniques:
- T1566
name: Trend Micro CAS - Unexpected file via mail
requiredDataConnectors:
- dataTypes:
  - TrendMicroCAS
  connectorId: TrendMicroCAS
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountCustomEntity
  entityType: Account
triggerThreshold: 0
id: 201fd2d1-9131-4b29-bace-ce5d19f3e4ee
tactics:
- InitialAccess
version: 1.0.0
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Trend Micro Cloud App Security/Analytic Rules/TrendMicroCASUnexpectedFileInMail.yaml
queryPeriod: 1h
kind: Scheduled
queryFrequency: 1h
severity: Medium
status: Available
description: |
    'Detects when unexpected file recieved via mail.'
query: |
  let f_types = dynamic(['ps1', 'bat', 'scr', 'sh', 'exe', 'js', 'lnk']);
  TrendMicroCAS
  | where EventCategoryType in~ ('exchange', 'gmail', 'exchangeserver')
  | where isnotempty(SrcFileName)
  | extend file_type = extract(@'\.(\w+)$', 1, SrcFileName)
  | where file_type in~ (f_types)
  | extend AccountCustomEntity = DstUserName  
triggerOperator: gt

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/201fd2d1-9131-4b29-bace-ce5d19f3e4ee')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/201fd2d1-9131-4b29-bace-ce5d19f3e4ee')]",
      "properties": {
        "alertRuleTemplateName": "201fd2d1-9131-4b29-bace-ce5d19f3e4ee",
        "customDetails": null,
        "description": "'Detects when unexpected file recieved via mail.'\n",
        "displayName": "Trend Micro CAS - Unexpected file via mail",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "Name"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Trend Micro Cloud App Security/Analytic Rules/TrendMicroCASUnexpectedFileInMail.yaml",
        "query": "let f_types = dynamic(['ps1', 'bat', 'scr', 'sh', 'exe', 'js', 'lnk']);\nTrendMicroCAS\n| where EventCategoryType in~ ('exchange', 'gmail', 'exchangeserver')\n| where isnotempty(SrcFileName)\n| extend file_type = extract(@'\\.(\\w+)$', 1, SrcFileName)\n| where file_type in~ (f_types)\n| extend AccountCustomEntity = DstUserName\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1566"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}