Suspicious granting of permissions to an account

Original query, unchanged.

let starttime = 14d;
let endtime = 1d;
// The number of operations above which an IP address is considered an unusual source of role assignment operations
let alertOperationThreshold = 5;
let AzureBuiltInRole = externaldata(Role:string,RoleDescription:string,ID:string) [@"https://raw.githubusercontent.com/Azure/Azure-Sentinel/master/Sample%20Data/Feeds/AzureBuiltInRole.csv"] with (format="csv", ignoreFirstRecord=True);
let createRoleAssignmentActivity = AzureActivity
| where OperationNameValue =~ "microsoft.authorization/roleassignments/write";
let RoleAssignedActivity = createRoleAssignmentActivity 
| where TimeGenerated between (ago(starttime) .. ago(endtime))
| summarize count() by CallerIpAddress, Caller, bin(TimeGenerated, 1d)
| where count_ >= alertOperationThreshold
// Returns all the records from the right side that don't have matches from the left.
| join kind = rightanti ( 
createRoleAssignmentActivity
| where TimeGenerated > ago(endtime)
| extend parsed_property = tostring(parse_json(Properties).requestbody)
| extend PrincipalId = case(parsed_property has_cs 'PrincipalId',parse_json(parsed_property).Properties.PrincipalId, parsed_property has_cs 'principalId',parse_json(parsed_property).properties.principalId,"")
| extend PrincipalType = case(parsed_property has_cs 'PrincipalType',parse_json(parsed_property).Properties.PrincipalType, parsed_property has_cs 'principalType',parse_json(parsed_property).properties.principalType, "")
| extend Scope = case(parsed_property has_cs 'Scope',parse_json(parsed_property).Properties.Scope, parsed_property has_cs 'scope',parse_json(parsed_property).properties.scope,"")
| extend RoleAddedDetails = case(parsed_property has_cs 'RoleDefinitionId',parse_json(parsed_property).Properties.RoleDefinitionId,parsed_property has_cs 'roleDefinitionId',parse_json(parsed_property).properties.roleDefinitionId,"")
| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), ActivityTimeStamp = make_set(TimeGenerated), ActivityStatusValue = make_set(ActivityStatusValue), CorrelationId = make_set(CorrelationId), ActivityCountByCallerIPAddress = count()  
by ResourceId, CallerIpAddress, Caller, OperationNameValue, Resource, ResourceGroup, PrincipalId, PrincipalType, Scope, RoleAddedDetails
) on CallerIpAddress, Caller
| extend timestamp = StartTimeUtc, AccountCustomEntity = Caller, IPCustomEntity = CallerIpAddress;
let RoleAssignedActivitywithRoleDetails = RoleAssignedActivity
| extend RoleAssignedID = tostring(split(RoleAddedDetails, "/")[-1])
// Returns all matching records from left and right sides.
| join kind = inner (AzureBuiltInRole 
) on $left.RoleAssignedID == $right.ID;
let CallerIPCountSummary = RoleAssignedActivitywithRoleDetails | summarize AssignmentCountbyCaller = count() by Caller, CallerIpAddress;
let RoleAssignedActivityWithCount = RoleAssignedActivitywithRoleDetails | join kind = inner (CallerIPCountSummary | project Caller, AssignmentCountbyCaller, CallerIpAddress) on Caller, CallerIpAddress;
RoleAssignedActivityWithCount
| summarize arg_max(StartTimeUtc, *) by PrincipalId, RoleAssignedID
// 	Returns all the records from the left side and only matching records from the right side.
| join kind = leftouter( IdentityInfo
| summarize arg_max(TimeGenerated, *) by AccountObjectId
) on $left.PrincipalId == $right.AccountObjectId
// Check if assignment count is greater than the threshold.
| where AssignmentCountbyCaller >= alertOperationThreshold
| project ActivityTimeStamp, OperationNameValue, Caller, CallerIpAddress, PrincipalId, RoleAssignedID, RoleAddedDetails, Role, RoleDescription, AccountUPN, AccountCreationTime, GroupMembership, UserType, ActivityStatusValue, ResourceGroup, PrincipalType, Scope, CorrelationId, timestamp, AccountCustomEntity, IPCustomEntity, AssignmentCountbyCaller
| extend Name = tostring(split(Caller,'@',0)[0]), UPNSuffix = tostring(split(Caller,'@',1)[0])