Trend Micro CAS - Unexpected file via mail

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Id	201fd2d1-9131-4b29-bace-ce5d19f3e4ee
Rulename	Trend Micro CAS - Unexpected file via mail
Description	Detects when unexpected file recieved via mail.
Severity	Medium
Tactics	InitialAccess
Techniques	T1566
Required data connectors	TrendMicroCAS
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Trend Micro Cloud App Security/Analytic Rules/TrendMicroCASUnexpectedFileInMail.yaml
Version	1.0.0
Arm template	201fd2d1-9131-4b29-bace-ce5d19f3e4ee.json

KQL

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

YAML

name: Trend Micro CAS - Unexpected file via mail
id: 201fd2d1-9131-4b29-bace-ce5d19f3e4ee
description: |
    'Detects when unexpected file recieved via mail.'
triggerThreshold: 0
entityMappings:
- fieldMappings:
  - columnName: AccountCustomEntity
    identifier: Name
  entityType: Account
version: 1.0.0
triggerOperator: gt
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  
tactics:
- InitialAccess
kind: Scheduled
queryFrequency: 1h
severity: Medium
queryPeriod: 1h
requiredDataConnectors:
- dataTypes:
  - TrendMicroCAS
  connectorId: TrendMicroCAS
status: Available
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Trend Micro Cloud App Security/Analytic Rules/TrendMicroCASUnexpectedFileInMail.yaml
relevantTechniques:
- T1566

ARM