PRODAFT USTA - TI map Domain to DnsEvents

let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let Domain_Indicators = ThreatIntelIndicators
  // Each USTA IoC feed uploads under its own SourceSystem ("PRODAFT USTA - Malicious URLs", etc.)
  | where SourceSystem startswith "PRODAFT USTA"
  | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
  | where IndicatorType == "domain-name"
  | extend DomainName = tolower(ObservableValue)
  | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
  | where TimeGenerated >= ago(ioc_lookBack)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
  | where IsActive and (ValidUntil > now() or isempty(ValidUntil));
// TLD allow-list built from the feed: lets the DnsEvents scan discard most rows before the join
let maxListSize = 100000;
let list_tlds = Domain_Indicators
  | extend parts = split(DomainName, '.')
  | extend tld = parts[(array_length(parts)-1)]
  | extend IndicatorId = tostring(split(Id, "--")[2])
  | summarize count() by tostring(tld)
  | project tld
  | summarize make_list(tld, maxListSize);
Domain_Indicators
 | project-reorder *, IsActive, Tags, TrafficLightProtocolLevel, DomainName, Type
  // innerunique: one match per indicator is enough to alert, and it keeps the join cheap
  | join kind=innerunique (
    DnsEvents
    | where TimeGenerated > ago(dt_lookBack)
    | where isnotempty(Name)
    // DnsEvents.Name keeps the queried casing; the indicator side is lowercased, and the join below is case-sensitive
    | extend Name = tolower(Name)
    | extend parts = split(Name, '.')
    | extend tld = parts[(array_length(parts)-1)]
    | where tld in~ (list_tlds)
    | extend DNS_TimeGenerated = TimeGenerated
  ) on $left.DomainName==$right.Name
  // non-expiring indicators are allowed above, so they must survive this filter too
  | where isempty(ValidUntil) or DNS_TimeGenerated < ValidUntil
  | summarize DNS_TimeGenerated = arg_max(DNS_TimeGenerated, *) by Id, Name
  | extend Description = tostring(parse_json(Data).description)
  | extend IndicatorTags = tostring(parse_json(Data).labels)
  | project DNS_TimeGenerated, Description, IndicatorTags, Id, ValidUntil, Confidence, Computer, ClientIP
  | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
  | extend timestamp = DNS_TimeGenerated

name: PRODAFT USTA - TI map Domain to DnsEvents
triggerOperator: gt
query: |
  let dt_lookBack = 1h;
  let ioc_lookBack = 14d;
  let Domain_Indicators = ThreatIntelIndicators
    // Each USTA IoC feed uploads under its own SourceSystem ("PRODAFT USTA - Malicious URLs", etc.)
    | where SourceSystem startswith "PRODAFT USTA"
    | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
    | where IndicatorType == "domain-name"
    | extend DomainName = tolower(ObservableValue)
    | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
    | where TimeGenerated >= ago(ioc_lookBack)
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
    | where IsActive and (ValidUntil > now() or isempty(ValidUntil));
  // TLD allow-list built from the feed: lets the DnsEvents scan discard most rows before the join
  let maxListSize = 100000;
  let list_tlds = Domain_Indicators
    | extend parts = split(DomainName, '.')
    | extend tld = parts[(array_length(parts)-1)]
    | extend IndicatorId = tostring(split(Id, "--")[2])
    | summarize count() by tostring(tld)
    | project tld
    | summarize make_list(tld, maxListSize);
  Domain_Indicators
   | project-reorder *, IsActive, Tags, TrafficLightProtocolLevel, DomainName, Type
    // innerunique: one match per indicator is enough to alert, and it keeps the join cheap
    | join kind=innerunique (
      DnsEvents
      | where TimeGenerated > ago(dt_lookBack)
      | where isnotempty(Name)
      // DnsEvents.Name keeps the queried casing; the indicator side is lowercased, and the join below is case-sensitive
      | extend Name = tolower(Name)
      | extend parts = split(Name, '.')
      | extend tld = parts[(array_length(parts)-1)]
      | where tld in~ (list_tlds)
      | extend DNS_TimeGenerated = TimeGenerated
    ) on $left.DomainName==$right.Name
    // non-expiring indicators are allowed above, so they must survive this filter too
    | where isempty(ValidUntil) or DNS_TimeGenerated < ValidUntil
    | summarize DNS_TimeGenerated = arg_max(DNS_TimeGenerated, *) by Id, Name
    | extend Description = tostring(parse_json(Data).description)
    | extend IndicatorTags = tostring(parse_json(Data).labels)
    | project DNS_TimeGenerated, Description, IndicatorTags, Id, ValidUntil, Confidence, Computer, ClientIP
    | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
    | extend timestamp = DNS_TimeGenerated
queryFrequency: 1h
description: |
  'Identifies a match in DnsEvents from any domain-name indicator ingested from PRODAFT USTA
  IoC Threat Intelligence (SourceSystem starting with "PRODAFT USTA").'
id: c6f85aff-4ef0-4fde-b90e-e0ba1a9c3df6
triggerThreshold: 0
queryPeriod: 14d
version: 1.0.0
kind: Scheduled
relevantTechniques:
- T1071
severity: Medium
requiredDataConnectors:
- connectorId: DNS
  dataTypes:
  - DnsEvents
- connectorId: PRODAFTUstaIoCUploadIndicators
  dataTypes:
  - ThreatIntelIndicators
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/PRODAFT%20USTA%20-%20IoC%20Threat%20Intelligence/Analytic%20Rules/TIMapDomainToDnsEvents.yaml
tactics:
- CommandAndControl
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: Computer
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: DnsDomain
  entityType: Host
- fieldMappings:
  - identifier: Address
    columnName: ClientIP
  entityType: IP

{
  "$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/c6f85aff-4ef0-4fde-b90e-e0ba1a9c3df6')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/c6f85aff-4ef0-4fde-b90e-e0ba1a9c3df6')]",
      "properties": {
        "alertRuleTemplateName": "c6f85aff-4ef0-4fde-b90e-e0ba1a9c3df6",
        "customDetails": null,
        "description": "'Identifies a match in DnsEvents from any domain-name indicator ingested from PRODAFT USTA\nIoC Threat Intelligence (SourceSystem starting with \"PRODAFT USTA\").'\n",
        "displayName": "PRODAFT USTA - TI map Domain to DnsEvents",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "Computer",
                "identifier": "FullName"
              },
              {
                "columnName": "HostName",
                "identifier": "HostName"
              },
              {
                "columnName": "DnsDomain",
                "identifier": "DnsDomain"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "ClientIP",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/PRODAFT%20USTA%20-%20IoC%20Threat%20Intelligence/Analytic%20Rules/TIMapDomainToDnsEvents.yaml",
        "query": "let dt_lookBack = 1h;\nlet ioc_lookBack = 14d;\nlet Domain_Indicators = ThreatIntelIndicators\n  // Each USTA IoC feed uploads under its own SourceSystem (\"PRODAFT USTA - Malicious URLs\", etc.)\n  | where SourceSystem startswith \"PRODAFT USTA\"\n  | extend IndicatorType = replace(@\"\\[|\\]|\\\"\"\", \"\", tostring(split(ObservableKey, \":\", 0)))\n  | where IndicatorType == \"domain-name\"\n  | extend DomainName = tolower(ObservableValue)\n  | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)\n  | where TimeGenerated >= ago(ioc_lookBack)\n  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue\n  | where IsActive and (ValidUntil > now() or isempty(ValidUntil));\n// TLD allow-list built from the feed: lets the DnsEvents scan discard most rows before the join\nlet maxListSize = 100000;\nlet list_tlds = Domain_Indicators\n  | extend parts = split(DomainName, '.')\n  | extend tld = parts[(array_length(parts)-1)]\n  | extend IndicatorId = tostring(split(Id, \"--\")[2])\n  | summarize count() by tostring(tld)\n  | project tld\n  | summarize make_list(tld, maxListSize);\nDomain_Indicators\n | project-reorder *, IsActive, Tags, TrafficLightProtocolLevel, DomainName, Type\n  // innerunique: one match per indicator is enough to alert, and it keeps the join cheap\n  | join kind=innerunique (\n    DnsEvents\n    | where TimeGenerated > ago(dt_lookBack)\n    | where isnotempty(Name)\n    // DnsEvents.Name keeps the queried casing; the indicator side is lowercased, and the join below is case-sensitive\n    | extend Name = tolower(Name)\n    | extend parts = split(Name, '.')\n    | extend tld = parts[(array_length(parts)-1)]\n    | where tld in~ (list_tlds)\n    | extend DNS_TimeGenerated = TimeGenerated\n  ) on $left.DomainName==$right.Name\n  // non-expiring indicators are allowed above, so they must survive this filter too\n  | where isempty(ValidUntil) or DNS_TimeGenerated < ValidUntil\n  | summarize DNS_TimeGenerated = arg_max(DNS_TimeGenerated, *) by Id, Name\n  | extend Description = tostring(parse_json(Data).description)\n  | extend IndicatorTags = tostring(parse_json(Data).labels)\n  | project DNS_TimeGenerated, Description, IndicatorTags, Id, ValidUntil, Confidence, Computer, ClientIP\n  | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))\n  | extend timestamp = DNS_TimeGenerated\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl"
        ],
        "techniques": [
          "T1071"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}