Digital Guardian - Exfiltration to private email

DigitalGuardianDLPEvent
| where NetworkApplicationProtocol =~ 'SMTP'
| where isnotempty(inspected_document)
| extend s_user = substring(SrcUserName, 0, indexof(SrcUserName, '@'))
| extend d_user = substring(DstUserName, 0, indexof(DstUserName, '@'))
| extend s_domain = extract(@'@(.*)', 1, SrcUserName)
| extend d_domain = extract(@'@(.*)', 1, DstUserName)
| where s_domain != d_domain
| where s_user == d_user
| extend AccountCustomEntity = SrcUserName

queryPeriod: 1h
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountCustomEntity
  entityType: Account
relevantTechniques:
- T1048
severity: High
requiredDataConnectors:
- connectorId: SyslogAma
  datatypes:
  - Syslog
id: edead9b5-243a-466b-ae78-2dae32ab1117
triggerOperator: gt
kind: Scheduled
query: |
  DigitalGuardianDLPEvent
  | where NetworkApplicationProtocol =~ 'SMTP'
  | where isnotempty(inspected_document)
  | extend s_user = substring(SrcUserName, 0, indexof(SrcUserName, '@'))
  | extend d_user = substring(DstUserName, 0, indexof(DstUserName, '@'))
  | extend s_domain = extract(@'@(.*)', 1, SrcUserName)
  | extend d_domain = extract(@'@(.*)', 1, DstUserName)
  | where s_domain != d_domain
  | where s_user == d_user
  | extend AccountCustomEntity = SrcUserName  
tactics:
- Exfiltration
triggerThreshold: 0
queryFrequency: 1h
status: Available
description: |
    'Detects exfiltration to private email.'
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Digital Guardian Data Loss Prevention/Analytic Rules/DigitalGuardianFileSentToExternal.yaml
name: Digital Guardian - Exfiltration to private email
version: 1.0.2

{
  "$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/edead9b5-243a-466b-ae78-2dae32ab1117')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/edead9b5-243a-466b-ae78-2dae32ab1117')]",
      "properties": {
        "alertRuleTemplateName": "edead9b5-243a-466b-ae78-2dae32ab1117",
        "customDetails": null,
        "description": "'Detects exfiltration to private email.'\n",
        "displayName": "Digital Guardian - Exfiltration to private email",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "Name"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Digital Guardian Data Loss Prevention/Analytic Rules/DigitalGuardianFileSentToExternal.yaml",
        "query": "DigitalGuardianDLPEvent\n| where NetworkApplicationProtocol =~ 'SMTP'\n| where isnotempty(inspected_document)\n| extend s_user = substring(SrcUserName, 0, indexof(SrcUserName, '@'))\n| extend d_user = substring(DstUserName, 0, indexof(DstUserName, '@'))\n| extend s_domain = extract(@'@(.*)', 1, SrcUserName)\n| extend d_domain = extract(@'@(.*)', 1, DstUserName)\n| where s_domain != d_domain\n| where s_user == d_user\n| extend AccountCustomEntity = SrcUserName\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "High",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Exfiltration"
        ],
        "techniques": [
          "T1048"
        ],
        "templateVersion": "1.0.2",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}