TI map Domain entity to DnsEvents

// Define the lookback periods for time-based filters
let dt_lookBack = 1h; // Look back 1 hour for DNS events
let ioc_lookBack = 14d; // Look back 14 days for threat intelligence indicators
// Fetch threat intelligence indicators related to domains
let Domain_Indicators = ThreatIntelligenceIndicator
  // Filter out indicators without domain names
  | where isnotempty(DomainName)
  | where TimeGenerated >= ago(ioc_lookBack)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true and ExpirationDateTime > now()
  | extend TI_DomainEntity = DomainName;
// Create a list of TLDs in our threat feed for later validation
let maxListSize = 100000; // Define the maximum allowed size for each list
let list_tlds = Domain_Indicators
  | extend parts = split(DomainName, '.')
  | extend tld = parts[(array_length(parts)-1)]
  | summarize count() by tostring(tld)
  | project tld
  | summarize make_list(tld, maxListSize);
// Perform a join between domain indicators and DNS events to identify potential malicious activity
Domain_Indicators
  // Use innerunique to keep performance fast and result set low, as we only need one match to indicate potential malicious activity that needs investigation
  | join kind=innerunique (
    DnsEvents
    | where TimeGenerated > ago(dt_lookBack)
    // Extract domain patterns from syslog message
    | where isnotempty(Name)
    | extend parts = split(Name, '.')
    | extend tld = parts[(array_length(parts)-1)]
    // Validate parsed domain by checking if the TLD is in the list of TLDs in our threat feed
    | where tld in~ (list_tlds)
    | extend DNS_TimeGenerated = TimeGenerated
  ) on $left.TI_DomainEntity==$right.Name
  // Filter out DNS events that occurred after the expiration of the corresponding indicator
  | where DNS_TimeGenerated < ExpirationDateTime
  // Group the results by IndicatorId and Name, and keep the DNS event with the latest timestamp
  | summarize DNS_TimeGenerated = arg_max(DNS_TimeGenerated, *) by IndicatorId, Name
  // Select the desired output fields
  | project DNS_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, Url, Computer, ClientIP, Name, QueryType, Type, TI_DomainEntity
  // Extract hostname and DNS domain from the Computer field
  | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
  // Rename the timestamp field
  | extend timestamp = DNS_TimeGenerated

relevantTechniques:
- T1071
name: TI map Domain entity to DnsEvents
requiredDataConnectors:
- dataTypes:
  - DnsEvents
  connectorId: DNS
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligence
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: ThreatIntelligenceTaxii
- dataTypes:
  - ThreatIntelligenceIndicator
  connectorId: MicrosoftDefenderThreatIntelligence
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: Computer
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: DnsDomain
  entityType: Host
- fieldMappings:
  - identifier: Address
    columnName: ClientIP
  entityType: IP
- fieldMappings:
  - identifier: Url
    columnName: Url
  entityType: URL
triggerThreshold: 0
id: 85aca4d1-5d15-4001-abd9-acb86ca1786a
tactics:
- CommandAndControl
version: 1.4.3
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/DomainEntity_DnsEvents.yaml
queryPeriod: 14d
kind: Scheduled
queryFrequency: 1h
severity: Medium
description: |
    Identifies a match in DnsEvents from any Domain IOC from TI
query: |
  // Define the lookback periods for time-based filters
  let dt_lookBack = 1h; // Look back 1 hour for DNS events
  let ioc_lookBack = 14d; // Look back 14 days for threat intelligence indicators
  // Fetch threat intelligence indicators related to domains
  let Domain_Indicators = ThreatIntelligenceIndicator
    // Filter out indicators without domain names
    | where isnotempty(DomainName)
    | where TimeGenerated >= ago(ioc_lookBack)
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
    | where Active == true and ExpirationDateTime > now()
    | extend TI_DomainEntity = DomainName;
  // Create a list of TLDs in our threat feed for later validation
  let maxListSize = 100000; // Define the maximum allowed size for each list
  let list_tlds = Domain_Indicators
    | extend parts = split(DomainName, '.')
    | extend tld = parts[(array_length(parts)-1)]
    | summarize count() by tostring(tld)
    | project tld
    | summarize make_list(tld, maxListSize);
  // Perform a join between domain indicators and DNS events to identify potential malicious activity
  Domain_Indicators
    // Use innerunique to keep performance fast and result set low, as we only need one match to indicate potential malicious activity that needs investigation
    | join kind=innerunique (
      DnsEvents
      | where TimeGenerated > ago(dt_lookBack)
      // Extract domain patterns from syslog message
      | where isnotempty(Name)
      | extend parts = split(Name, '.')
      | extend tld = parts[(array_length(parts)-1)]
      // Validate parsed domain by checking if the TLD is in the list of TLDs in our threat feed
      | where tld in~ (list_tlds)
      | extend DNS_TimeGenerated = TimeGenerated
    ) on $left.TI_DomainEntity==$right.Name
    // Filter out DNS events that occurred after the expiration of the corresponding indicator
    | where DNS_TimeGenerated < ExpirationDateTime
    // Group the results by IndicatorId and Name, and keep the DNS event with the latest timestamp
    | summarize DNS_TimeGenerated = arg_max(DNS_TimeGenerated, *) by IndicatorId, Name
    // Select the desired output fields
    | project DNS_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, Url, Computer, ClientIP, Name, QueryType, Type, TI_DomainEntity
    // Extract hostname and DNS domain from the Computer field
    | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
    // Rename the timestamp field
    | extend timestamp = DNS_TimeGenerated  
triggerOperator: gt

{
  "$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/85aca4d1-5d15-4001-abd9-acb86ca1786a')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/85aca4d1-5d15-4001-abd9-acb86ca1786a')]",
      "properties": {
        "alertRuleTemplateName": "85aca4d1-5d15-4001-abd9-acb86ca1786a",
        "customDetails": null,
        "description": "Identifies a match in DnsEvents from any Domain IOC from TI\n",
        "displayName": "TI map Domain entity 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"
              }
            ]
          },
          {
            "entityType": "URL",
            "fieldMappings": [
              {
                "columnName": "Url",
                "identifier": "Url"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Threat Intelligence/Analytic Rules/DomainEntity_DnsEvents.yaml",
        "query": "// Define the lookback periods for time-based filters\nlet dt_lookBack = 1h; // Look back 1 hour for DNS events\nlet ioc_lookBack = 14d; // Look back 14 days for threat intelligence indicators\n// Fetch threat intelligence indicators related to domains\nlet Domain_Indicators = ThreatIntelligenceIndicator\n  // Filter out indicators without domain names\n  | where isnotempty(DomainName)\n  | where TimeGenerated >= ago(ioc_lookBack)\n  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId\n  | where Active == true and ExpirationDateTime > now()\n  | extend TI_DomainEntity = DomainName;\n// Create a list of TLDs in our threat feed for later validation\nlet maxListSize = 100000; // Define the maximum allowed size for each list\nlet list_tlds = Domain_Indicators\n  | extend parts = split(DomainName, '.')\n  | extend tld = parts[(array_length(parts)-1)]\n  | summarize count() by tostring(tld)\n  | project tld\n  | summarize make_list(tld, maxListSize);\n// Perform a join between domain indicators and DNS events to identify potential malicious activity\nDomain_Indicators\n  // Use innerunique to keep performance fast and result set low, as we only need one match to indicate potential malicious activity that needs investigation\n  | join kind=innerunique (\n    DnsEvents\n    | where TimeGenerated > ago(dt_lookBack)\n    // Extract domain patterns from syslog message\n    | where isnotempty(Name)\n    | extend parts = split(Name, '.')\n    | extend tld = parts[(array_length(parts)-1)]\n    // Validate parsed domain by checking if the TLD is in the list of TLDs in our threat feed\n    | where tld in~ (list_tlds)\n    | extend DNS_TimeGenerated = TimeGenerated\n  ) on $left.TI_DomainEntity==$right.Name\n  // Filter out DNS events that occurred after the expiration of the corresponding indicator\n  | where DNS_TimeGenerated < ExpirationDateTime\n  // Group the results by IndicatorId and Name, and keep the DNS event with the latest timestamp\n  | summarize DNS_TimeGenerated = arg_max(DNS_TimeGenerated, *) by IndicatorId, Name\n  // Select the desired output fields\n  | project DNS_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, ExpirationDateTime, ConfidenceScore, Url, Computer, ClientIP, Name, QueryType, Type, TI_DomainEntity\n  // Extract hostname and DNS domain from the Computer field\n  | extend HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))\n  // Rename the timestamp field\n  | extend timestamp = DNS_TimeGenerated\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CommandAndControl"
        ],
        "techniques": [
          "T1071"
        ],
        "templateVersion": "1.4.3",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}