Microsoft COVID-19 file hash indicator matches

Original query, unchanged.

let dt_lookBack = 1h;
let covidIndicators = (externaldata(TimeGenerated:datetime, FileHashValue:string, FileHashType: string, TlpLevel: string, Product: string, ThreatType: string, Description: string )
[@"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/Microsoft.Covid19.Indicators.csv"] with (format="csv"));
let fileHashIndicators = covidIndicators
| where isnotempty(FileHashValue);
// Handle matches against both lower case and uppercase versions of the hash:
(fileHashIndicators | extend FileHashValue = tolower(FileHashValue)
| union (fileHashIndicators | extend FileHashValue = toupper(FileHashValue)))
// using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
|  join kind=innerunique (
   CommonSecurityLog | where TimeGenerated >= ago(dt_lookBack)
   | where isnotempty(FileHash)
   | extend CommonSecurityLog_TimeGenerated = TimeGenerated
   )
on $left.FileHashValue == $right.FileHash
| summarize CommonSecurityLog_TimeGenerated = arg_max(CommonSecurityLog_TimeGenerated, *) by FileHashValue
| project CommonSecurityLog_TimeGenerated, FileHashValue, FileHashType, Description, ThreatType,
SourceIP, SourcePort, DestinationIP, DestinationPort, SourceUserID, SourceUserName, DeviceName, DeviceAction,
RequestURL, DestinationUserName, DestinationUserID, ApplicationProtocol, Activity
| extend AccountName = tostring(split(SourceUserName, "@")[0]), AccountUPNSuffix = tostring(split(SourceUserName, "@")[1])
| extend HostName = tostring(split(DeviceName, ".")[0]), DomainIndex = toint(indexof(DeviceName, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(DeviceName, DomainIndex + 1), DeviceName)