SlackAudit - Suspicious file downloaded

SlackAudit
| where DvcAction =~ 'file_downloaded'
| extend fe = split(EntityFileName, '.')
| where array_length(fe) > 2
| where fe[1] matches regex @"\D+"
| where strlen(fe[1]) < 5
| project EntityFileName, SrcUserName
| extend AccountCustomEntity = SrcUserName
| extend FileCustomEntity = EntityFileName

relevantTechniques:
- T1189
name: SlackAudit - Suspicious file downloaded.
requiredDataConnectors:
- dataTypes:
  - SlackAudit_CL
  connectorId: SlackAuditAPI
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: AccountCustomEntity
  entityType: Account
- fieldMappings:
  - identifier: Name
    columnName: FileCustomEntity
  entityType: File
triggerThreshold: 0
id: 132b98a5-07e9-401a-9b6f-453e52a53979
tactics:
- InitialAccess
version: 1.0.0
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/SlackAudit/Analytic Rules/SlackAuditSuspiciousFileDownloaded.yaml
queryPeriod: 1h
kind: Scheduled
queryFrequency: 1h
severity: Medium
status: Available
description: |
    'Detects potentialy suspicious downloads.'
query: |
  SlackAudit
  | where DvcAction =~ 'file_downloaded'
  | extend fe = split(EntityFileName, '.')
  | where array_length(fe) > 2
  | where fe[1] matches regex @"\D+"
  | where strlen(fe[1]) < 5
  | project EntityFileName, SrcUserName
  | extend AccountCustomEntity = SrcUserName
  | extend FileCustomEntity = EntityFileName  
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/132b98a5-07e9-401a-9b6f-453e52a53979')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/132b98a5-07e9-401a-9b6f-453e52a53979')]",
      "properties": {
        "alertRuleTemplateName": "132b98a5-07e9-401a-9b6f-453e52a53979",
        "customDetails": null,
        "description": "'Detects potentialy suspicious downloads.'\n",
        "displayName": "SlackAudit - Suspicious file downloaded.",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountCustomEntity",
                "identifier": "FullName"
              }
            ]
          },
          {
            "entityType": "File",
            "fieldMappings": [
              {
                "columnName": "FileCustomEntity",
                "identifier": "Name"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/SlackAudit/Analytic Rules/SlackAuditSuspiciousFileDownloaded.yaml",
        "query": "SlackAudit\n| where DvcAction =~ 'file_downloaded'\n| extend fe = split(EntityFileName, '.')\n| where array_length(fe) > 2\n| where fe[1] matches regex @\"\\D+\"\n| where strlen(fe[1]) < 5\n| project EntityFileName, SrcUserName\n| extend AccountCustomEntity = SrcUserName\n| extend FileCustomEntity = EntityFileName\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "techniques": [
          "T1189"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}