Trend Micro CAS - Suspicious filename

TrendMicroCAS
| where isnotempty(SrcFileName)
| where SrcFileName matches regex @'\A[a-zA-Z0-9_\-.]{1,3}\.\w+$'
| extend AccountCustomEntity = DstUserName

relevantTechniques:
- T1566
name: Trend Micro CAS - Suspicious filename
requiredDataConnectors:
- dataTypes:
  - TrendMicroCAS
  connectorId: TrendMicroCAS
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountCustomEntity
  entityType: Account
triggerThreshold: 0
id: 52c4640a-1e2b-4155-b69e-e1869c9a57c9
tactics:
- InitialAccess
version: 1.0.0
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Trend Micro Cloud App Security/Analytic Rules/TrendMicroCASSuspiciousFilename.yaml
queryPeriod: 1h
kind: Scheduled
queryFrequency: 1h
severity: Medium
status: Available
description: |
    'Detects unexpected filename.'
query: |
  TrendMicroCAS
  | where isnotempty(SrcFileName)
  | where SrcFileName matches regex @'\A[a-zA-Z0-9_\-.]{1,3}\.\w+$'
  | extend AccountCustomEntity = DstUserName  
triggerOperator: gt

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/52c4640a-1e2b-4155-b69e-e1869c9a57c9')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/52c4640a-1e2b-4155-b69e-e1869c9a57c9')]",
      "properties": {
        "alertRuleTemplateName": "52c4640a-1e2b-4155-b69e-e1869c9a57c9",
        "customDetails": null,
        "description": "'Detects unexpected filename.'\n",
        "displayName": "Trend Micro CAS - Suspicious filename",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "Name"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Trend Micro Cloud App Security/Analytic Rules/TrendMicroCASSuspiciousFilename.yaml",
        "query": "TrendMicroCAS\n| where isnotempty(SrcFileName)\n| where SrcFileName matches regex @'\\A[a-zA-Z0-9_\\-.]{1,3}\\.\\w+$'\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"
    }
  ]
}