Potential DGADomain Generation Algorithm detected via Repetitive Failures - Anomaly based ASIM DNS Solution

let threshold = 2.5;
let min_t = ago(14d);
let max_t = now();
let timeframe = 1d;
// calculate avg. eps(events per second)
let eps = materialize (_Im_Dns
  | project TimeGenerated
  | where TimeGenerated > ago(5m)
  | count
  | extend Count = Count / 300);
let maxSummarizedTime = toscalar (
  union isfuzzy=true 
      (
      DNS_Summarized_Logs_ip_CL 
      | where EventTime_t >= min_t
      | summarize max_TimeGenerated=max(EventTime_t)
      | extend max_TimeGenerated = datetime_add('hour', 1, max_TimeGenerated)
      ),
      (
      print(min_t)
      | project max_TimeGenerated = print_0
      )
  | summarize maxTimeGenerated = max(max_TimeGenerated) 
  );
let summarizationexist = materialize(
  union isfuzzy=true 
      (
      DNS_Summarized_Logs_ip_CL
      | where EventTime_t > ago(1d) 
      | project v = int(2)
      ),
      (
      print int(1) 
      | project v = print_0
      )
  | summarize maxv = max(v)
  | extend sumexist = (maxv > 1)
  );
let allData = union isfuzzy=true
      (
      (datatable(exists: int, sumexist: bool)[1, false]
      | where toscalar(eps) > 1000
      | join (summarizationexist) on sumexist)
      | join (
          _Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(2d)), endtime=now())
          | where TimeGenerated > maxSummarizedTime
          | summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)
          | extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)
          )
          on exists
      | project-away exists, maxv, sum*
      ),
      (
      (datatable(exists: int, sumexist: bool)[1, false]
      | where toscalar(eps) between (501 .. 1000)
      | join (summarizationexist) on sumexist)
      | join (
          _Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(3d)), endtime=now())
          | where TimeGenerated > maxSummarizedTime
          | summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)
          | extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)
          )
          on exists
      | project-away exists, maxv, sum*
      ),
      (
      (datatable(exists: int, sumexist: bool)[1, false]
      | where toscalar(eps) <= 500
      | join (summarizationexist) on sumexist)
      | join (
          _Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(4d)), endtime=now())
          | where TimeGenerated > maxSummarizedTime
          | summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)
          | extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)
          )
          on exists
      | project-away exists, maxv, sum*
      ),
      (
      DNS_Summarized_Logs_ip_CL
      | where EventTime_t > min_t and EventResultDetails_s == 'NXDOMAIN'
      | project-rename
          SrcIpAddr=SrcIpAddr_s,
          DnsQuery=DnsQuery_s,
          Count=count__d,
          EventTime=EventTime_t
      | extend Count = toint(Count)
      );
allData
| make-series QueryCount=dcount(DnsQuery) on EventTime from min_t to max_t step timeframe by SrcIpAddr
// include calculated Anomalies, Score and Baseline
| extend (anomalies, score, baseline) = series_decompose_anomalies(QueryCount, threshold, -1, 'linefit')
| mv-expand anomalies, score, baseline, EventTime, QueryCount
| extend
  anomalies = toint(anomalies),
  score = toint(score),
  baseline = toint(baseline),
  EventTime = todatetime(EventTime),
  Total = tolong(QueryCount)
| where EventTime >= ago(timeframe)
| where score >= threshold * 2
// Join allData to include DnsQuery details
| join kind=inner(allData
  | where TimeGenerated >= ago(timeframe)
  | summarize DNSQueries = make_set(DnsQuery, 1000) by SrcIpAddr)
  on SrcIpAddr
| project-away SrcIpAddr1

relevantTechniques:
- T1568
- T1008
name: Potential DGA(Domain Generation Algorithm) detected via Repetitive Failures - Anomaly based (ASIM DNS Solution)
requiredDataConnectors: []
entityMappings:
- fieldMappings:
  - identifier: Address
    columnName: SrcIpAddr
  entityType: IP
triggerThreshold: 0
id: 01191239-274e-43c9-b154-3a042692af06
tactics:
- CommandAndControl
version: 1.0.2
customDetails:
  baseline: baseline
  DNSQueries: DNSQueries
  Total: Total
  AnomalyScore: score
queryPeriod: 14d
alertDetailsOverride:
  alertDisplayNameFormat: "[Anomaly] Potential DGA (Domain Generation Algorithm) originating from client IP: '{{SrcIpAddr}}' has been detected."
  alertDescriptionFormat: |-
    Client has been identified with high NXDomain count which could be indicative of a DGA (cycling through possible C2 domains where most C2s are not live). This client is found to be communicating with multiple Domains which do not exist.

    Baseline Domain or DNS query count from this client: '{{baseline}}'

    Current Domain or DNS query count from this client: '{{Total}}'

    DNS queries requested by this client inlcude: '{{DNSQueries}}'    
triggerOperator: gt
kind: Scheduled
tags:
- Schema: ASimDns
  SchemaVersion: 0.1.6
eventGroupingSettings:
  aggregationKind: AlertPerResult
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/DNS Essentials/Analytic Rules/PotentialDGADetectedviaRepetitiveFailuresAnomalyBased.yaml
queryFrequency: 1d
severity: Medium
status: Available
description: |
    'This rule makes use of the series decompose anomaly method to detect clients with a high NXDomain response count, which could be indicative of a DGA (cycling through possible C2 domains where most C2s are not live). An alert is generated when new IP address DNS activity is identified as an outlier when compared to the baseline, indicating a recurring pattern. It utilizes [ASIM](https://aka.ms/AboutASIM) normalization and is applied to any source that supports the ASIM DNS schema.'
query: |
  let threshold = 2.5;
  let min_t = ago(14d);
  let max_t = now();
  let timeframe = 1d;
  // calculate avg. eps(events per second)
  let eps = materialize (_Im_Dns
    | project TimeGenerated
    | where TimeGenerated > ago(5m)
    | count
    | extend Count = Count / 300);
  let maxSummarizedTime = toscalar (
    union isfuzzy=true 
        (
        DNS_Summarized_Logs_ip_CL 
        | where EventTime_t >= min_t
        | summarize max_TimeGenerated=max(EventTime_t)
        | extend max_TimeGenerated = datetime_add('hour', 1, max_TimeGenerated)
        ),
        (
        print(min_t)
        | project max_TimeGenerated = print_0
        )
    | summarize maxTimeGenerated = max(max_TimeGenerated) 
    );
  let summarizationexist = materialize(
    union isfuzzy=true 
        (
        DNS_Summarized_Logs_ip_CL
        | where EventTime_t > ago(1d) 
        | project v = int(2)
        ),
        (
        print int(1) 
        | project v = print_0
        )
    | summarize maxv = max(v)
    | extend sumexist = (maxv > 1)
    );
  let allData = union isfuzzy=true
        (
        (datatable(exists: int, sumexist: bool)[1, false]
        | where toscalar(eps) > 1000
        | join (summarizationexist) on sumexist)
        | join (
            _Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(2d)), endtime=now())
            | where TimeGenerated > maxSummarizedTime
            | summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)
            | extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)
            )
            on exists
        | project-away exists, maxv, sum*
        ),
        (
        (datatable(exists: int, sumexist: bool)[1, false]
        | where toscalar(eps) between (501 .. 1000)
        | join (summarizationexist) on sumexist)
        | join (
            _Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(3d)), endtime=now())
            | where TimeGenerated > maxSummarizedTime
            | summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)
            | extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)
            )
            on exists
        | project-away exists, maxv, sum*
        ),
        (
        (datatable(exists: int, sumexist: bool)[1, false]
        | where toscalar(eps) <= 500
        | join (summarizationexist) on sumexist)
        | join (
            _Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(4d)), endtime=now())
            | where TimeGenerated > maxSummarizedTime
            | summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)
            | extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)
            )
            on exists
        | project-away exists, maxv, sum*
        ),
        (
        DNS_Summarized_Logs_ip_CL
        | where EventTime_t > min_t and EventResultDetails_s == 'NXDOMAIN'
        | project-rename
            SrcIpAddr=SrcIpAddr_s,
            DnsQuery=DnsQuery_s,
            Count=count__d,
            EventTime=EventTime_t
        | extend Count = toint(Count)
        );
  allData
  | make-series QueryCount=dcount(DnsQuery) on EventTime from min_t to max_t step timeframe by SrcIpAddr
  // include calculated Anomalies, Score and Baseline
  | extend (anomalies, score, baseline) = series_decompose_anomalies(QueryCount, threshold, -1, 'linefit')
  | mv-expand anomalies, score, baseline, EventTime, QueryCount
  | extend
    anomalies = toint(anomalies),
    score = toint(score),
    baseline = toint(baseline),
    EventTime = todatetime(EventTime),
    Total = tolong(QueryCount)
  | where EventTime >= ago(timeframe)
  | where score >= threshold * 2
  // Join allData to include DnsQuery details
  | join kind=inner(allData
    | where TimeGenerated >= ago(timeframe)
    | summarize DNSQueries = make_set(DnsQuery, 1000) by SrcIpAddr)
    on SrcIpAddr
  | project-away SrcIpAddr1  

{
  "$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/01191239-274e-43c9-b154-3a042692af06')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/01191239-274e-43c9-b154-3a042692af06')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "Client has been identified with high NXDomain count which could be indicative of a DGA (cycling through possible C2 domains where most C2s are not live). This client is found to be communicating with multiple Domains which do not exist.\n\nBaseline Domain or DNS query count from this client: '{{baseline}}'\n\nCurrent Domain or DNS query count from this client: '{{Total}}'\n\nDNS queries requested by this client inlcude: '{{DNSQueries}}'",
          "alertDisplayNameFormat": "[Anomaly] Potential DGA (Domain Generation Algorithm) originating from client IP: '{{SrcIpAddr}}' has been detected."
        },
        "alertRuleTemplateName": "01191239-274e-43c9-b154-3a042692af06",
        "customDetails": {
          "AnomalyScore": "score",
          "baseline": "baseline",
          "DNSQueries": "DNSQueries",
          "Total": "Total"
        },
        "description": "'This rule makes use of the series decompose anomaly method to detect clients with a high NXDomain response count, which could be indicative of a DGA (cycling through possible C2 domains where most C2s are not live). An alert is generated when new IP address DNS activity is identified as an outlier when compared to the baseline, indicating a recurring pattern. It utilizes [ASIM](https://aka.ms/AboutASIM) normalization and is applied to any source that supports the ASIM DNS schema.'\n",
        "displayName": "Potential DGA(Domain Generation Algorithm) detected via Repetitive Failures - Anomaly based (ASIM DNS Solution)",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SrcIpAddr",
                "identifier": "Address"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "AlertPerResult"
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/DNS Essentials/Analytic Rules/PotentialDGADetectedviaRepetitiveFailuresAnomalyBased.yaml",
        "query": "let threshold = 2.5;\nlet min_t = ago(14d);\nlet max_t = now();\nlet timeframe = 1d;\n// calculate avg. eps(events per second)\nlet eps = materialize (_Im_Dns\n  | project TimeGenerated\n  | where TimeGenerated > ago(5m)\n  | count\n  | extend Count = Count / 300);\nlet maxSummarizedTime = toscalar (\n  union isfuzzy=true \n      (\n      DNS_Summarized_Logs_ip_CL \n      | where EventTime_t >= min_t\n      | summarize max_TimeGenerated=max(EventTime_t)\n      | extend max_TimeGenerated = datetime_add('hour', 1, max_TimeGenerated)\n      ),\n      (\n      print(min_t)\n      | project max_TimeGenerated = print_0\n      )\n  | summarize maxTimeGenerated = max(max_TimeGenerated) \n  );\nlet summarizationexist = materialize(\n  union isfuzzy=true \n      (\n      DNS_Summarized_Logs_ip_CL\n      | where EventTime_t > ago(1d) \n      | project v = int(2)\n      ),\n      (\n      print int(1) \n      | project v = print_0\n      )\n  | summarize maxv = max(v)\n  | extend sumexist = (maxv > 1)\n  );\nlet allData = union isfuzzy=true\n      (\n      (datatable(exists: int, sumexist: bool)[1, false]\n      | where toscalar(eps) > 1000\n      | join (summarizationexist) on sumexist)\n      | join (\n          _Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(2d)), endtime=now())\n          | where TimeGenerated > maxSummarizedTime\n          | summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)\n          | extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)\n          )\n          on exists\n      | project-away exists, maxv, sum*\n      ),\n      (\n      (datatable(exists: int, sumexist: bool)[1, false]\n      | where toscalar(eps) between (501 .. 1000)\n      | join (summarizationexist) on sumexist)\n      | join (\n          _Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(3d)), endtime=now())\n          | where TimeGenerated > maxSummarizedTime\n          | summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)\n          | extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)\n          )\n          on exists\n      | project-away exists, maxv, sum*\n      ),\n      (\n      (datatable(exists: int, sumexist: bool)[1, false]\n      | where toscalar(eps) <= 500\n      | join (summarizationexist) on sumexist)\n      | join (\n          _Im_Dns(responsecodename='NXDOMAIN', starttime=todatetime(ago(4d)), endtime=now())\n          | where TimeGenerated > maxSummarizedTime\n          | summarize Count=count() by SrcIpAddr, DnsQuery, bin(TimeGenerated, 1h)\n          | extend EventTime = TimeGenerated, Count = toint(Count), exists=int(1)\n          )\n          on exists\n      | project-away exists, maxv, sum*\n      ),\n      (\n      DNS_Summarized_Logs_ip_CL\n      | where EventTime_t > min_t and EventResultDetails_s == 'NXDOMAIN'\n      | project-rename\n          SrcIpAddr=SrcIpAddr_s,\n          DnsQuery=DnsQuery_s,\n          Count=count__d,\n          EventTime=EventTime_t\n      | extend Count = toint(Count)\n      );\nallData\n| make-series QueryCount=dcount(DnsQuery) on EventTime from min_t to max_t step timeframe by SrcIpAddr\n// include calculated Anomalies, Score and Baseline\n| extend (anomalies, score, baseline) = series_decompose_anomalies(QueryCount, threshold, -1, 'linefit')\n| mv-expand anomalies, score, baseline, EventTime, QueryCount\n| extend\n  anomalies = toint(anomalies),\n  score = toint(score),\n  baseline = toint(baseline),\n  EventTime = todatetime(EventTime),\n  Total = tolong(QueryCount)\n| where EventTime >= ago(timeframe)\n| where score >= threshold * 2\n// Join allData to include DnsQuery details\n| join kind=inner(allData\n  | where TimeGenerated >= ago(timeframe)\n  | summarize DNSQueries = make_set(DnsQuery, 1000) by SrcIpAddr)\n  on SrcIpAddr\n| project-away SrcIpAddr1\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl"
        ],
        "tags": [
          {
            "Schema": "ASimDns",
            "SchemaVersion": "0.1.6"
          }
        ],
        "techniques": [
          "T1008",
          "T1568"
        ],
        "templateVersion": "1.0.2",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}