Local Admin Group Changes

Original query, unchanged.

let machineAccountSIDs = dynamic([
  "S-1-5-18",
  "S-1-5-20",
  "S-1-5-19"]);
let ADAZUsers =  IdentityInfo 
| extend DirectoryDomain = AccountDomain 
| extend DirectoryAccount = AccountName 
| extend OnPremSid = AccountSID
| distinct DirectoryDomain , DirectoryAccount , OnPremSid , AccountCloudSID, AccountUPN, GivenName, Surname;
 // check for any new created or modified local accounts 
let NewUsers =  DeviceEvents
| where ActionType contains "UserAccountCreated" or ActionType contains "UserAccountModified"
| extend lUserAdded = AccountName
| extend NewUserSID = AccountSid
| extend laccountdomain = AccountDomain
| distinct NewUserSID, lUserAdded,laccountdomain;
// Check for any local group changes and enrich the data with the account name obtained from the previous query
DeviceEvents 
| where ActionType == 'UserAccountAddedToLocalGroup'
// Exclude machine and wellknown SIDs 
| where (AccountSid !in (machineAccountSIDs)) and (AccountSid matches regex @"S-\d-\d+-\d+-(\d+-){1,5}\d+")
| extend LocalGroupSID = tostring(parse_json(AdditionalFields).GroupSid)
| extend LocalGroup = tostring(parse_json(AdditionalFields).GroupName)
| extend AddedAccountSID = AccountSid
| extend Actor = trim(@"[^\w]+",InitiatingProcessAccountName)
// limit to local administrators group
// | where LocalGroupSID contains "S-1-5-32-544"
| join kind=leftouter    (NewUsers)
on $left.AddedAccountSID == $right.NewUserSID
| project TimeGenerated, DeviceName, LocalGroup,LocalGroupSID, AddedAccountSID, lUserAdded , Actor, ActionType , laccountdomain 
| join kind=innerunique  (ADAZUsers)
on $left.AddedAccountSID == $right.OnPremSid
| extend UserAdded = iff(isnotempty(lUserAdded),strcat(laccountdomain,"\\", lUserAdded), strcat(DirectoryDomain,"\\", DirectoryAccount))
| extend AccountName = iff(isnotempty(lUserAdded), lUserAdded, DirectoryAccount)
| project TimeGenerated, DeviceName, LocalGroup, LocalGroupSID, AddedAccountSID, UserAdded ,Actor, ActionType, AccountName, laccountdomain  
| where DeviceName !contains Actor
// Provide details on actors that added users
// | summarize count()  by Actor 
// | join ADAZUsers
// on $left.Actor == $right.DirectoryAccount 
// | render piechart
| extend HostName = iff(DeviceName has '.', substring(DeviceName, 0, indexof(DeviceName, '.')), DeviceName)
| extend DnsDomain = iff(DeviceName has '.', substring(DeviceName, indexof(DeviceName, '.') + 1), "")