Digital Guardian - Exfiltration to external domain

let corp_domain = dynamic(['example.com']);     //add all corporate domains to this list
DigitalGuardianDLPEvent
| where NetworkApplicationProtocol =~ 'SMTP'
| where isnotempty(inspected_document)
| extend s_domain = extract(@'@(.*)', 1, SrcUserName)
| extend d_domain = extract(@'@(.*)', 1, DstUserName)
| where s_domain in~ (corp_domain)
| where d_domain !in (corp_domain)
| extend AccountCustomEntity = SrcUserName

name: Digital Guardian - Exfiltration to external domain
kind: Scheduled
tactics:
- Exfiltration
triggerThreshold: 0
triggerOperator: gt
version: 1.0.2
status: Available
queryFrequency: 1h
id: a19885c8-1e44-47e3-81df-d1d109f5c92d
requiredDataConnectors:
- connectorId: SyslogAma
  datatypes:
  - Syslog
relevantTechniques:
- T1048
description: |
    'Detects exfiltration to external domain.'
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/DigitalGuardianFileSentToExternalDomain.yaml
queryPeriod: 1h
severity: Medium
query: |
  let corp_domain = dynamic(['example.com']);     //add all corporate domains to this list
  DigitalGuardianDLPEvent
  | where NetworkApplicationProtocol =~ 'SMTP'
  | where isnotempty(inspected_document)
  | extend s_domain = extract(@'@(.*)', 1, SrcUserName)
  | extend d_domain = extract(@'@(.*)', 1, DstUserName)
  | where s_domain in~ (corp_domain)
  | where d_domain !in (corp_domain)
  | extend AccountCustomEntity = SrcUserName