GreyNoise TI map IP entity to OfficeActivity

Original query, unchanged.

let dt_lookBack = 1h; // Look back 1 hour for OfficeActivity 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 OfficeActivity 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 (
      OfficeActivity
      | where TimeGenerated >= ago(dt_lookBack)
      | where isnotempty(ClientIP)
      | extend ClientIPValues = extract_all(@'\[?(::ffff:)?(?P<IPAddress>(\d+\.\d+\.\d+\.\d+)|[^\]%]+)(%\d+)?\]?([-:](?P<Port>\d+))?', dynamic(["IPAddress", "Port"]), ClientIP)[0]
      | extend IPAddress = iff(array_length(ClientIPValues) > 0, tostring(ClientIPValues[0]), '')
      | extend OfficeActivity_TimeGenerated = TimeGenerated
  )
  on $left.TI_ipEntity == $right.IPAddress
  // Filter out OfficeActivity events that occurred after the expiration of the corresponding indicator
  | where OfficeActivity_TimeGenerated < ExpirationDateTime
  // Group the results by IndicatorId and keep the OfficeActivity event with the latest timestamp
  | summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by IndicatorId
  // Select the desired output fields
  | project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore,
    TI_ipEntity, ClientIP, UserId, Operation, ResultStatus, RecordType, OfficeObjectId, NetworkIP, NetworkDestinationIP, NetworkSourceIP, EmailSourceIpAddress, Type
  | extend timestamp = OfficeActivity_TimeGenerated, Name = tostring(split(UserId, '@', 0)[0]), UPNSuffix = tostring(split(UserId, '@', 1)[0])