Account Created and Deleted in Short Timeframe

Original query, unchanged.

let queryfrequency = 1h;
let queryperiod = 7d; // Increased queryperiod to 7 days to mitigate timing-based bypasses
AuditLogs
| where TimeGenerated > ago(queryfrequency)
| where OperationName =~ "Delete user"
| mv-apply TargetResource = TargetResources on 
  (
      where TargetResource.type == "User"
      // Normalize TargetUserPrincipalName by removing optional 32-char hex prefixes and underscores
      // Making extraction case-insensitive, and converting the result to lowercase for consistency
      | extend TargetUserPrincipalName = tolower(extract(@"(?i)([a-f0-9]{32})?_?(.*)", 2, tostring(TargetResource.userPrincipalName)))
      // Standardize UserId to ensure consistent, immutable identification
      | extend UserId = tostring(TargetResource.id)
  )
| extend DeletedByApp = tostring(InitiatedBy.app.displayName),
DeletedByAppServicePrincipalId = tostring(InitiatedBy.app.servicePrincipalId),
DeletedByUserPrincipalName = tostring(InitiatedBy.user.userPrincipalName),
DeletedByAadUserId = tostring(InitiatedBy.user.id),
DeletedByIPAddress = tostring(InitiatedBy.user.ipAddress)
| project Deletion_TimeGenerated = TimeGenerated, TargetUserPrincipalName, UserId, DeletedByApp, DeletedByAppServicePrincipalId, DeletedByUserPrincipalName, DeletedByAadUserId, DeletedByIPAddress, 
Deletion_AdditionalDetails = AdditionalDetails, Deletion_InitiatedBy = InitiatedBy, Deletion_TargetResources = TargetResources
| join kind=inner (
    AuditLogs
    | where TimeGenerated > ago(queryperiod)
    | where OperationName =~ "Add user"      
    | mv-apply TargetResource = TargetResources on 
      (
          where TargetResource.type == "User"
          // Normalize TargetUserPrincipalName by removing optional 32-char hex prefixes and underscores
          // Making extraction case-insensitive, and converting the result to lowercase for consistency
          | extend TargetUserPrincipalName = tolower(extract(@"(?i)([a-f0-9]{32})?_?(.*)", 2, tostring(TargetResource.userPrincipalName)))
          // Standardize UserId to ensure consistent, immutable identification
          | extend UserId = tostring(TargetResource.id)
      )
    | project-rename Creation_TimeGenerated = TimeGenerated
) on UserId
| extend TimeDelta = Deletion_TimeGenerated - Creation_TimeGenerated
| where  TimeDelta between (time(0s) .. queryperiod)
| extend CreatedByApp = tostring(InitiatedBy.app.displayName),
CreatedByAppServicePrincipalId = tostring(InitiatedBy.app.servicePrincipalId),
CreatedByUserPrincipalName = tostring(InitiatedBy.user.userPrincipalName),
CreatedByAadUserId = tostring(InitiatedBy.user.id),
CreatedByIPAddress = tostring(InitiatedBy.user.ipAddress)
| project Creation_TimeGenerated, Deletion_TimeGenerated, TimeDelta, UserId, TargetUserPrincipalName, DeletedByApp, DeletedByAppServicePrincipalId, DeletedByUserPrincipalName, DeletedByAadUserId, DeletedByIPAddress, 
CreatedByApp, CreatedByAppServicePrincipalId, CreatedByUserPrincipalName, CreatedByAadUserId, CreatedByIPAddress, Creation_AdditionalDetails = AdditionalDetails, Creation_InitiatedBy = InitiatedBy, Creation_TargetResources = TargetResources, Deletion_AdditionalDetails, Deletion_InitiatedBy, Deletion_TargetResources
| extend TargetName = tostring(split(TargetUserPrincipalName,'@',0)[0]), TargetUPNSuffix = tostring(split(TargetUserPrincipalName,'@',1)[0])
| extend CreatedByName = tostring(split(CreatedByUserPrincipalName,'@',0)[0]), CreatedByUPNSuffix = tostring(split(CreatedByUserPrincipalName,'@',1)[0])
| extend DeletedByName = tostring(split(DeletedByUserPrincipalName,'@',0)[0]), DeletedByUPNSuffix = tostring(split(DeletedByUserPrincipalName,'@',1)[0])