GreyNoise TI Map IP Entity to DnsEvents

Original query, unchanged.

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 = ThreatIntelligenceIndicator
  | where TimeGenerated >= ago(ioc_lookBack)
  | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
  | where Active == true and ExpirationDateTime > now()
  | where SourceSystem == 'GreyNoise'
  | where isnotempty(NetworkIP) or isnotempty(EmailSourceIpAddress) or isnotempty(NetworkDestinationIP) or isnotempty(NetworkSourceIP)
  | extend TI_ipEntity = iff(isnotempty(NetworkIP), NetworkIP, NetworkDestinationIP)
  | extend TI_ipEntity = iff(isempty(TI_ipEntity) and isnotempty(NetworkSourceIP), NetworkSourceIP, TI_ipEntity)
  | extend TI_ipEntity = iff(isempty(TI_ipEntity) and isnotempty(EmailSourceIpAddress), EmailSourceIpAddress, TI_ipEntity)
  | where ipv4_is_private(TI_ipEntity) == false and  TI_ipEntity !startswith "fe80" and TI_ipEntity !startswith "::" and TI_ipEntity !startswith "127.";
// Perform a join between IP indicators and DNS events
IP_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)
      | 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 < ExpirationDateTime
  // Group the results by IndicatorId and SingleIP, and keep the DNS event with the latest timestamp
  | summarize DNS_TimeGenerated = arg_max(DNS_TimeGenerated, *) by IndicatorId, SingleIP
  // Select the desired output fields
  | project DNS_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, DomainName, ExpirationDateTime, ConfidenceScore,
    TI_ipEntity, Computer, EventId, SubType, ClientIP, Name, IPAddresses, NetworkIP, NetworkDestinationIP, NetworkSourceIP, EmailSourceIpAddress, Type
  | extend timestamp = DNS_TimeGenerated, HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))