winload.exe

logsource:
  category: process_creation
  product: windows
detection:
  selection:
    - Image|endswith: '\winload.exe'
    - OriginalFileName: 'osloader.exe'
  condition: selection

| tstats summariesonly=false count values(Processes.original_file_name) as original_file_name
    from datamodel=Endpoint.Processes
    where (Processes.original_file_name="osloader.exe" OR Processes.process_name="winload.exe")
    by Processes.dest Processes.process_name Processes.process_path Processes.process
| rename Processes.* as *

DeviceProcessEvents
| where ProcessVersionInfoOriginalFileName in~ ("osloader.exe")
    or FileName =~ "winload.exe"

process where event.type == "start" and
  (process.pe.original_file_name in~ ("osloader.exe") or
   process.name : "winload.exe")

['osloader.exe'].includes(String(OriginalFileName || '').toLowerCase())