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

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Id89ba52fa-96a7-4653-829a-ca49bb13336c
RulenamePotential DGA(Domain Generation Algorithm) detected via Repetitive Failures - Static threshold based (ASIM DNS Solution)
DescriptionThis rule 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). An 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). It utilizes ASIM normalization and is applied to any source that supports the ASIM DNS schema.
SeverityMedium
TacticsCommandAndControl
TechniquesT1568
T1008
KindScheduled
Query frequency1d
Query period10d
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Solutions/DNS Essentials/Analytic Rules/PotentialDGADetectedviaRepetitiveFailuresStaticThresholdBased.yaml
Version1.0.2
Arm template89ba52fa-96a7-4653-829a-ca49bb13336c.json
Deploy To Azure
let threshold = 100;
let lookback = 10d;
let referenceendtime = 1d;
let nxDomainDnsEvents = (stime: datetime, etime: datetime) {
  _Im_Dns(responsecodename='NXDOMAIN', starttime=stime, endtime=etime)
  | where DnsQueryTypeName in ("A", "AAAA")
  | where ipv4_is_match("127.0.0.1", SrcIpAddr) == False
  | where DnsQuery !contains "/" and DnsQuery contains "."
};
nxDomainDnsEvents (stime=ago(referenceendtime), etime=now())
| summarize
  StartTimeUtc = min(TimeGenerated),
  EndTimeUtc = max(TimeGenerated),
  DNSQueryCount=dcount(DnsQuery)
  by SrcIpAddr
| where DNSQueryCount > threshold
// Filter out previously seen IPs
| join kind=leftanti (nxDomainDnsEvents (stime=ago(lookback), etime=ago(referenceendtime))
  | summarize DNSQueryCount=dcount(DnsQuery) by SrcIpAddr, bin(TimeGenerated,1d)
  | where DNSQueryCount > threshold)
  on SrcIpAddr
// Pull out sample NXDomain responses for those remaining potentially infected IPs
| join kind = inner (nxDomainDnsEvents (stime=ago(lookback), etime=now())
  | summarize by DnsQuery, SrcIpAddr)
  on SrcIpAddr
| summarize
  StartTimeUtc = min(StartTimeUtc),
  EndTimeUtc = max(EndTimeUtc),
  DNSQueries=make_list(DnsQuery, 100)
  by SrcIpAddr, DNSQueryCount
| extend DNSQueryThreshold=threshold
customDetails:
  DNSQueryCount: DNSQueryCount
  DNSQueryThreshold: DNSQueryThreshold
  DNSQueries: DNSQueries
alertDetailsOverride:
  alertDisplayNameFormat: "[Static threshold] 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.

    DGA DNS query count baseline is: '{{DNSQueryThreshold}}'

    Current failed DNS query count from this client: '{{DNSQueryCount}}'

    DNS queries requested by this client inlcude: '{{DNSQueries}}'    
eventGroupingSettings:
  aggregationKind: AlertPerResult
tags:
- Schema: ASimDns
  SchemaVersion: 0.1.6
status: Available
triggerThreshold: 0
relevantTechniques:
- T1568
- T1008
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/DNS Essentials/Analytic Rules/PotentialDGADetectedviaRepetitiveFailuresStaticThresholdBased.yaml
requiredDataConnectors: []
queryPeriod: 10d
tactics:
- CommandAndControl
severity: Medium
triggerOperator: gt
description: |
    'This rule 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). An 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). It utilizes [ASIM](https://aka.ms/AboutASIM) normalization and is applied to any source that supports the ASIM DNS schema.'
query: |
  let threshold = 100;
  let lookback = 10d;
  let referenceendtime = 1d;
  let nxDomainDnsEvents = (stime: datetime, etime: datetime) {
    _Im_Dns(responsecodename='NXDOMAIN', starttime=stime, endtime=etime)
    | where DnsQueryTypeName in ("A", "AAAA")
    | where ipv4_is_match("127.0.0.1", SrcIpAddr) == False
    | where DnsQuery !contains "/" and DnsQuery contains "."
  };
  nxDomainDnsEvents (stime=ago(referenceendtime), etime=now())
  | summarize
    StartTimeUtc = min(TimeGenerated),
    EndTimeUtc = max(TimeGenerated),
    DNSQueryCount=dcount(DnsQuery)
    by SrcIpAddr
  | where DNSQueryCount > threshold
  // Filter out previously seen IPs
  | join kind=leftanti (nxDomainDnsEvents (stime=ago(lookback), etime=ago(referenceendtime))
    | summarize DNSQueryCount=dcount(DnsQuery) by SrcIpAddr, bin(TimeGenerated,1d)
    | where DNSQueryCount > threshold)
    on SrcIpAddr
  // Pull out sample NXDomain responses for those remaining potentially infected IPs
  | join kind = inner (nxDomainDnsEvents (stime=ago(lookback), etime=now())
    | summarize by DnsQuery, SrcIpAddr)
    on SrcIpAddr
  | summarize
    StartTimeUtc = min(StartTimeUtc),
    EndTimeUtc = max(EndTimeUtc),
    DNSQueries=make_list(DnsQuery, 100)
    by SrcIpAddr, DNSQueryCount
  | extend DNSQueryThreshold=threshold  
name: Potential DGA(Domain Generation Algorithm) detected via Repetitive Failures - Static threshold based (ASIM DNS Solution)
version: 1.0.2
kind: Scheduled
id: 89ba52fa-96a7-4653-829a-ca49bb13336c
queryFrequency: 1d
entityMappings:
- entityType: IP
  fieldMappings:
  - columnName: SrcIpAddr
    identifier: Address
{
  "$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/89ba52fa-96a7-4653-829a-ca49bb13336c')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/89ba52fa-96a7-4653-829a-ca49bb13336c')]",
      "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\nDGA DNS query count baseline is: '{{DNSQueryThreshold}}'\n\nCurrent failed DNS query count from this client: '{{DNSQueryCount}}'\n\nDNS queries requested by this client inlcude: '{{DNSQueries}}'",
          "alertDisplayNameFormat": "[Static threshold] Potential DGA (Domain Generation Algorithm) originating from client IP: '{{SrcIpAddr}}' has been detected."
        },
        "alertRuleTemplateName": "89ba52fa-96a7-4653-829a-ca49bb13336c",
        "customDetails": {
          "DNSQueries": "DNSQueries",
          "DNSQueryCount": "DNSQueryCount",
          "DNSQueryThreshold": "DNSQueryThreshold"
        },
        "description": "'This rule 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). An 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). 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 - Static threshold 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/PotentialDGADetectedviaRepetitiveFailuresStaticThresholdBased.yaml",
        "query": "let threshold = 100;\nlet lookback = 10d;\nlet referenceendtime = 1d;\nlet nxDomainDnsEvents = (stime: datetime, etime: datetime) {\n  _Im_Dns(responsecodename='NXDOMAIN', starttime=stime, endtime=etime)\n  | where DnsQueryTypeName in (\"A\", \"AAAA\")\n  | where ipv4_is_match(\"127.0.0.1\", SrcIpAddr) == False\n  | where DnsQuery !contains \"/\" and DnsQuery contains \".\"\n};\nnxDomainDnsEvents (stime=ago(referenceendtime), etime=now())\n| summarize\n  StartTimeUtc = min(TimeGenerated),\n  EndTimeUtc = max(TimeGenerated),\n  DNSQueryCount=dcount(DnsQuery)\n  by SrcIpAddr\n| where DNSQueryCount > threshold\n// Filter out previously seen IPs\n| join kind=leftanti (nxDomainDnsEvents (stime=ago(lookback), etime=ago(referenceendtime))\n  | summarize DNSQueryCount=dcount(DnsQuery) by SrcIpAddr, bin(TimeGenerated,1d)\n  | where DNSQueryCount > threshold)\n  on SrcIpAddr\n// Pull out sample NXDomain responses for those remaining potentially infected IPs\n| join kind = inner (nxDomainDnsEvents (stime=ago(lookback), etime=now())\n  | summarize by DnsQuery, SrcIpAddr)\n  on SrcIpAddr\n| summarize\n  StartTimeUtc = min(StartTimeUtc),\n  EndTimeUtc = max(EndTimeUtc),\n  DNSQueries=make_list(DnsQuery, 100)\n  by SrcIpAddr, DNSQueryCount\n| extend DNSQueryThreshold=threshold\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P10D",
        "severity": "Medium",
        "status": "Available",
        "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"
    }
  ]
}