Solutions/Threat Intelligence (NEW)/Analytic Rules/IPEntity_DnsEvents.yaml

id: 6418fd33-92f2-407b-bd61-91c0d4bbcb8a
name: TI Map IP Entity to DnsEvents
description: |
  This query maps any IP indicators of compromise (IOCs) from threat intelligence (TI), by searching for matches in DnsEvents.
severity: Medium
requiredDataConnectors:
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: DNS
    dataTypes:
      - DnsEvents
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
relevantTechniques:
  - T1071
query: |
  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 IP addresses
  let IP_Indicators = ThreatIntelIndicators
  //extract key part of kv pair
  | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
       | where isnotempty(IndicatorType) and IndicatorType == "ipv4-addr"
       | extend NetworkSourceIP = toupper(ObservableValue)
       | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
    | where isnotempty(NetworkSourceIP)
    | where TimeGenerated >= ago(ioc_lookBack)
    | extend TI_ipEntity = iff(isnotempty(NetworkSourceIP), NetworkSourceIP, NetworkSourceIP)
    | extend TI_ipEntity = iff(isempty(TI_ipEntity) and isnotempty(NetworkSourceIP), NetworkSourceIP, TI_ipEntity)
    | extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
    | where ipv4_is_private(TI_ipEntity) == false and  TI_ipEntity !startswith "fe80" and TI_ipEntity !startswith "::" and TI_ipEntity !startswith "127."
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id
    | where IsActive == true and ValidUntil > now();
  // Perform a join between IP indicators and DNS events
  IP_Indicators
     | project-reorder *, Tags, TrafficLightProtocolLevel, NetworkSourceIP, Type, TI_ipEntity
    // 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)
        | where SubType =~ "LookupQuery" and isnotempty(IPAddresses)
        | mv-expand SingleIP = split(IPAddresses, ", ") to typeof(string)
        | extend DNS_TimeGenerated = TimeGenerated
    )
    on $left.TI_ipEntity == $right.SingleIP
    // Filter out DNS events that occurred after the expiration of the corresponding indicator
    | where DNS_TimeGenerated < ValidUntil
    // Group the results by IndicatorId and SingleIP, and keep the DNS event with the latest timestamp
    | summarize DNS_TimeGenerated = arg_max(DNS_TimeGenerated, *) by Id, SingleIP
    // Select the desired output fields
    | extend Description = tostring(parse_json(Data).description)
    | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
    | project DNS_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, TI_ipEntity, Computer, EventId, SubType, ClientIP, Name, IPAddresses, NetworkSourceIP, Type, Url
    | extend timestamp = DNS_TimeGenerated, HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Computer
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: ClientIP
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
version: 1.4.5
kind: Scheduled