Potential DGA detected

let starttime = 10d;
let endtime = 1d;
let threshold = 100;
let nxDomainDnsEvents = DnsEvents
| where ResultCode == 3
| where QueryType in ("A", "AAAA")
| where ipv4_is_match("127.0.0.1", ClientIP) == False
| where Name !contains "/"
| where Name contains ".";
nxDomainDnsEvents
| where TimeGenerated > ago(endtime)
| extend sld = tostring(split(Name, ".")[-2])
| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), dcount(sld) by ClientIP
| where dcount_sld > threshold
// Filter out previously seen IPs
| join kind=leftanti (nxDomainDnsEvents
    | where TimeGenerated between(ago(starttime)..ago(endtime))
    | extend sld = tostring(split(Name, ".")[-2])
    | summarize dcount(sld) by ClientIP
    | where dcount_sld > threshold ) on ClientIP
// Pull out sample NXDomain responses for those remaining potentially infected IPs
| join kind = inner (nxDomainDnsEvents | summarize by Name, ClientIP) on ClientIP
| summarize StartTimeUtc = min(StartTimeUtc), EndTimeUtc = max(EndTimeUtc), sampleNXDomainList=make_list(Name, 100)  by ClientIP, dcount_sld
| extend timestamp = StartTimeUtc, IPCustomEntity = ClientIP

queryFrequency: 1d
triggerOperator: gt
tactics:
- CommandAndControl
description: |
  'Identifies clients with a high NXDomain count which could be indicative of a DGA (cycling through possible C2 domains
  where most C2s are not live). Alert is generated when a new IP address is seen (based on not being seen associated with
  NXDomain records in prior 10-day baseline period).'  
status: Available
relevantTechniques:
- T1568
- T1008
name: Potential DGA detected
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows Server DNS/Analytic Rules/DNS_HighNXDomainCount_detection.yaml
severity: Medium
triggerThreshold: 0
version: 1.0.1
entityMappings:
- entityType: IP
  fieldMappings:
  - identifier: Address
    columnName: IPCustomEntity
query: |
  let starttime = 10d;
  let endtime = 1d;
  let threshold = 100;
  let nxDomainDnsEvents = DnsEvents
  | where ResultCode == 3
  | where QueryType in ("A", "AAAA")
  | where ipv4_is_match("127.0.0.1", ClientIP) == False
  | where Name !contains "/"
  | where Name contains ".";
  nxDomainDnsEvents
  | where TimeGenerated > ago(endtime)
  | extend sld = tostring(split(Name, ".")[-2])
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), dcount(sld) by ClientIP
  | where dcount_sld > threshold
  // Filter out previously seen IPs
  | join kind=leftanti (nxDomainDnsEvents
      | where TimeGenerated between(ago(starttime)..ago(endtime))
      | extend sld = tostring(split(Name, ".")[-2])
      | summarize dcount(sld) by ClientIP
      | where dcount_sld > threshold ) on ClientIP
  // Pull out sample NXDomain responses for those remaining potentially infected IPs
  | join kind = inner (nxDomainDnsEvents | summarize by Name, ClientIP) on ClientIP
  | summarize StartTimeUtc = min(StartTimeUtc), EndTimeUtc = max(EndTimeUtc), sampleNXDomainList=make_list(Name, 100)  by ClientIP, dcount_sld
  | extend timestamp = StartTimeUtc, IPCustomEntity = ClientIP  
id: a0907abe-6925-4d90-af2b-c7e89dc201a6
requiredDataConnectors:
- connectorId: DNS
  dataTypes:
  - DnsEvents
kind: Scheduled
queryPeriod: 10d

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/a0907abe-6925-4d90-af2b-c7e89dc201a6')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/a0907abe-6925-4d90-af2b-c7e89dc201a6')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01",
      "properties": {
        "displayName": "Potential DGA detected",
        "description": "'Identifies clients with a high NXDomain count which could be indicative of a DGA (cycling through possible C2 domains\nwhere most C2s are not live). Alert is generated when a new IP address is seen (based on not being seen associated with\nNXDomain records in prior 10-day baseline period).'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "let starttime = 10d;\nlet endtime = 1d;\nlet threshold = 100;\nlet nxDomainDnsEvents = DnsEvents\n| where ResultCode == 3\n| where QueryType in (\"A\", \"AAAA\")\n| where ipv4_is_match(\"127.0.0.1\", ClientIP) == False\n| where Name !contains \"/\"\n| where Name contains \".\";\nnxDomainDnsEvents\n| where TimeGenerated > ago(endtime)\n| extend sld = tostring(split(Name, \".\")[-2])\n| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), dcount(sld) by ClientIP\n| where dcount_sld > threshold\n// Filter out previously seen IPs\n| join kind=leftanti (nxDomainDnsEvents\n    | where TimeGenerated between(ago(starttime)..ago(endtime))\n    | extend sld = tostring(split(Name, \".\")[-2])\n    | summarize dcount(sld) by ClientIP\n    | where dcount_sld > threshold ) on ClientIP\n// Pull out sample NXDomain responses for those remaining potentially infected IPs\n| join kind = inner (nxDomainDnsEvents | summarize by Name, ClientIP) on ClientIP\n| summarize StartTimeUtc = min(StartTimeUtc), EndTimeUtc = max(EndTimeUtc), sampleNXDomainList=make_list(Name, 100)  by ClientIP, dcount_sld\n| extend timestamp = StartTimeUtc, IPCustomEntity = ClientIP\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P10D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl"
        ],
        "techniques": [
          "T1568",
          "T1008"
        ],
        "alertRuleTemplateName": "a0907abe-6925-4d90-af2b-c7e89dc201a6",
        "customDetails": null,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "identifier": "Address",
                "columnName": "IPCustomEntity"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows Server DNS/Analytic Rules/DNS_HighNXDomainCount_detection.yaml",
        "status": "Available",
        "templateVersion": "1.0.1"
      }
    }
  ]
}