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Cisco Umbrella - Request to blocklisted file type

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Idde58ee9e-b229-4252-8537-41a4c2f4045e
RulenameCisco Umbrella - Request to blocklisted file type
DescriptionDetects request to potentially harmful file types (.ps1, .bat, .vbs, etc.).
SeverityMedium
TacticsInitialAccess
Required data connectorsCiscoUmbrellaDataConnector
KindScheduled
Query frequency10m
Query period10m
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Detections/CiscoUmbrella/CiscoUmbrellaRequestBlocklistedFileType.yaml
Version1.0.1
Arm templatede58ee9e-b229-4252-8537-41a4c2f4045e.json
Deploy To Azure
let file_ext_blocklist = dynamic(['.ps1', '.vbs', '.bat', '.scr']);
let lbtime = 10m;
Cisco_Umbrella
| where TimeGenerated > ago(lbtime)
| where EventType == 'proxylogs'
| where DvcAction =~ 'Allowed'
| extend file_ext = extract(@'.*(\.\w+)$', 1, UrlOriginal)
| extend Filename = extract(@'.*\/*\/(.*\.\w+)$', 1, UrlOriginal)
| where file_ext in (file_ext_blocklist)
| project TimeGenerated, SrcIpAddr, Identities, Filename
triggerOperator: gt
queryFrequency: 10m
description: |
    'Detects request to potentially harmful file types (.ps1, .bat, .vbs, etc.).'
version: 1.0.1
kind: Scheduled
triggerThreshold: 0
requiredDataConnectors:
- connectorId: CiscoUmbrellaDataConnector
  dataTypes:
  - Cisco_Umbrella_proxy_CL
queryPeriod: 10m
name: Cisco Umbrella - Request to blocklisted file type
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/CiscoUmbrella/CiscoUmbrellaRequestBlocklistedFileType.yaml
id: de58ee9e-b229-4252-8537-41a4c2f4045e
tactics:
- InitialAccess
severity: Medium
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: Identities
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: SrcIpAddr
  entityType: IP
query: |
  let file_ext_blocklist = dynamic(['.ps1', '.vbs', '.bat', '.scr']);
  let lbtime = 10m;
  Cisco_Umbrella
  | where TimeGenerated > ago(lbtime)
  | where EventType == 'proxylogs'
  | where DvcAction =~ 'Allowed'
  | extend file_ext = extract(@'.*(\.\w+)$', 1, UrlOriginal)
  | extend Filename = extract(@'.*\/*\/(.*\.\w+)$', 1, UrlOriginal)
  | where file_ext in (file_ext_blocklist)
  | project TimeGenerated, SrcIpAddr, Identities, Filename  
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/de58ee9e-b229-4252-8537-41a4c2f4045e')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/de58ee9e-b229-4252-8537-41a4c2f4045e')]",
      "properties": {
        "alertRuleTemplateName": "de58ee9e-b229-4252-8537-41a4c2f4045e",
        "customDetails": null,
        "description": "'Detects request to potentially harmful file types (.ps1, .bat, .vbs, etc.).'\n",
        "displayName": "Cisco Umbrella - Request to blocklisted file type",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "Identities",
                "identifier": "FullName"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SrcIpAddr",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/CiscoUmbrella/CiscoUmbrellaRequestBlocklistedFileType.yaml",
        "query": "let file_ext_blocklist = dynamic(['.ps1', '.vbs', '.bat', '.scr']);\nlet lbtime = 10m;\nCisco_Umbrella\n| where TimeGenerated > ago(lbtime)\n| where EventType == 'proxylogs'\n| where DvcAction =~ 'Allowed'\n| extend file_ext = extract(@'.*(\\.\\w+)$', 1, UrlOriginal)\n| extend Filename = extract(@'.*\\/*\\/(.*\\.\\w+)$', 1, UrlOriginal)\n| where file_ext in (file_ext_blocklist)\n| project TimeGenerated, SrcIpAddr, Identities, Filename\n",
        "queryFrequency": "PT10M",
        "queryPeriod": "PT10M",
        "severity": "Medium",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "InitialAccess"
        ],
        "templateVersion": "1.0.1",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}