Ngrok Reverse Proxy on Network ASIM DNS Solution

// Define a list of Ngrok domains
let NgrokDomains = dynamic(["ngrok.com", "ngrok.io", "ngrok", "tunnel.com", "korgn", "lennut.com"]);
// Query the _Im_Dns function for the past 1 hour
_Im_Dns(starttime=ago(1h))
| where isnotempty(DnsQuery) // Filter out empty DNS queries
| where DnsQuery has_any (NgrokDomains) // Filter DNS queries that match any of the Ngrok domains
| summarize Starttime = min(EventStartTime),Endtime=max(EventEndTime),EventsCount=sum(EventCount),EventResults=make_set(EventResult,4) by DnsQuery, Domain, SrcIpAddr, Dvc
// Summarize the data by Domain, DNS query, source IP address, and device Dvc

requiredDataConnectors: []
query: |
  // Define a list of Ngrok domains
  let NgrokDomains = dynamic(["ngrok.com", "ngrok.io", "ngrok", "tunnel.com", "korgn", "lennut.com"]);
  // Query the _Im_Dns function for the past 1 hour
  _Im_Dns(starttime=ago(1h))
  | where isnotempty(DnsQuery) // Filter out empty DNS queries
  | where DnsQuery has_any (NgrokDomains) // Filter DNS queries that match any of the Ngrok domains
  | summarize Starttime = min(EventStartTime),Endtime=max(EventEndTime),EventsCount=sum(EventCount),EventResults=make_set(EventResult,4) by DnsQuery, Domain, SrcIpAddr, Dvc
  // Summarize the data by Domain, DNS query, source IP address, and device Dvc  
version: 1.0.0
triggerOperator: gt
queryPeriod: 1h
triggerThreshold: 0
kind: Scheduled
status: Available
relevantTechniques:
- T1572
- T1090
- T1102
name: Ngrok Reverse Proxy on Network (ASIM DNS Solution)
description: |
    'This detection identifies the top four Ngrok domains from DNS resolution. Ngrok reverse proxy can bypass network defense. While not inherently harmful, it has been used for malicious activities recently.'
severity: Medium
tactics:
- CommandAndControl
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/DNS Essentials/Analytic Rules/NgrokReverseProxyOnNetwork.yaml
entityMappings:
- entityType: IP
  fieldMappings:
  - columnName: SrcIpAddr
    identifier: Address
- entityType: DNS
  fieldMappings:
  - columnName: Domain
    identifier: DomainName
queryFrequency: 1h
eventGroupingSettings:
  aggregationKind: AlertPerResult
tags:
- SchemaVersion: 0.1.6
  Schema: ASimDns
id: 50b0dfb7-2c94-4eaf-a332-a5936d78c263

{
  "$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/50b0dfb7-2c94-4eaf-a332-a5936d78c263')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/50b0dfb7-2c94-4eaf-a332-a5936d78c263')]",
      "properties": {
        "alertRuleTemplateName": "50b0dfb7-2c94-4eaf-a332-a5936d78c263",
        "customDetails": null,
        "description": "'This detection identifies the top four Ngrok domains from DNS resolution. Ngrok reverse proxy can bypass network defense. While not inherently harmful, it has been used for malicious activities recently.'\n",
        "displayName": "Ngrok Reverse Proxy on Network (ASIM DNS Solution)",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SrcIpAddr",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "DNS",
            "fieldMappings": [
              {
                "columnName": "Domain",
                "identifier": "DomainName"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "AlertPerResult"
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/DNS Essentials/Analytic Rules/NgrokReverseProxyOnNetwork.yaml",
        "query": "// Define a list of Ngrok domains\nlet NgrokDomains = dynamic([\"ngrok.com\", \"ngrok.io\", \"ngrok\", \"tunnel.com\", \"korgn\", \"lennut.com\"]);\n// Query the _Im_Dns function for the past 1 hour\n_Im_Dns(starttime=ago(1h))\n| where isnotempty(DnsQuery) // Filter out empty DNS queries\n| where DnsQuery has_any (NgrokDomains) // Filter DNS queries that match any of the Ngrok domains\n| summarize Starttime = min(EventStartTime),Endtime=max(EventEndTime),EventsCount=sum(EventCount),EventResults=make_set(EventResult,4) by DnsQuery, Domain, SrcIpAddr, Dvc\n// Summarize the data by Domain, DNS query, source IP address, and device Dvc\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl"
        ],
        "tags": [
          {
            "Schema": "ASimDns",
            "SchemaVersion": "0.1.6"
          }
        ],
        "techniques": [
          "T1090",
          "T1102",
          "T1572"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}