Corelight - SMTP Email containing NON Ascii Characters within the Subject

Corelight
| where EventType =~ 'smtp'
| where Subject hasprefix  @'\=?utf-16'
| summarize recipients = dcount(To)
| extend k = 1
| join (Corelight
        | where Subject hasprefix  @'\=?utf-16'
        | summarize by To
        | extend k = 1) on k
| where recipients > 1
| extend MailCustomEntity = To

severity: Low
queryFrequency: 1h
relevantTechniques:
- T1566
tactics:
- InitialAccess
kind: Scheduled
query: |
  Corelight
  | where EventType =~ 'smtp'
  | where Subject hasprefix  @'\=?utf-16'
  | summarize recipients = dcount(To)
  | extend k = 1
  | join (Corelight
          | where Subject hasprefix  @'\=?utf-16'
          | summarize by To
          | extend k = 1) on k
  | where recipients > 1
  | extend MailCustomEntity = To  
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Corelight/Analytic Rules/CorelightSMTPEmailSubjectNonAsciiCharacters.yaml
queryPeriod: 1h
status: Available
version: 1.0.0
name: Corelight - SMTP Email containing NON Ascii Characters within the Subject
requiredDataConnectors:
- dataTypes:
  - Corelight
  connectorId: Corelight
triggerOperator: gt
entityMappings:
- entityType: MailMessage
  fieldMappings:
  - identifier: Recipient
    columnName: MailCustomEntity
id: 50c61708-9824-46f3-87cf-22490796fae2
description: |
    'Detects where an emails contain non ascii characters within the Subject.'
triggerThreshold: 0

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/50c61708-9824-46f3-87cf-22490796fae2')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/50c61708-9824-46f3-87cf-22490796fae2')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01-preview",
      "properties": {
        "displayName": "Corelight - SMTP Email containing NON Ascii Characters within the Subject",
        "description": "'Detects where an emails contain non ascii characters within the Subject.'\n",
        "severity": "Low",
        "enabled": true,
        "query": "Corelight\n| where EventType =~ 'smtp'\n| where Subject hasprefix  @'\\=?utf-16'\n| summarize recipients = dcount(To)\n| extend k = 1\n| join (Corelight\n        | where Subject hasprefix  @'\\=?utf-16'\n        | summarize by To\n        | extend k = 1) on k\n| where recipients > 1\n| extend MailCustomEntity = To\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1566"
        ],
        "alertRuleTemplateName": "50c61708-9824-46f3-87cf-22490796fae2",
        "customDetails": null,
        "entityMappings": [
          {
            "fieldMappings": [
              {
                "columnName": "MailCustomEntity",
                "identifier": "Recipient"
              }
            ],
            "entityType": "MailMessage"
          }
        ],
        "templateVersion": "1.0.0",
        "status": "Available",
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Corelight/Analytic Rules/CorelightSMTPEmailSubjectNonAsciiCharacters.yaml"
      }
    }
  ]
}