Process Creation Using Sysnative Folder (Windows Event Log)

id: '23146.42110'
title: Process Creation Using Sysnative Folder
description: 'Threat actors may use tools spawning processes from the Sysnative folder
  in an attempt to bypass the File System Redirector on 64-bit versions of Windows
  to execute 32-bit applications from the 64-bit system directory. This use cased
  detects instances where the Sysnative folder is used during process creation, a
  tactic often associated with CobaltStrike activities. Note: Sysnative is often referenced
  by legitimate processes. Allowlisting known processes is recommended to reduce false
  positives.'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
  "<EventID>4688<" OR Type=Process) "Sysnative" | regex process="(?i)^[A-Z]:\x5cWindows\x5cSysnative\x5c"
  | table _time, host, user, parent_process_name, process | bin span=1s | stats values(*)
  as * by _time, host '
techniques: 
- defense-evasion:system binary proxy execution
technique_id:
- T1218
data_category:
- Process command-line parameters
- Windows event logs
references:
- https://thedfirreport.com/2021/08/29/cobalt-strike-a-defenders-guide/
- https://learn.microsoft.com/sv-se/windows/win32/winprog64/file-system-redirector