Windows: New Executables Named After System Processes in Non-System Paths

title: "Windows: New Executables Named After System Processes in Non-System Paths"
id: 3cb1f029-54d8-440d-a5cf-068288d96be3
status: test
description: This rule flags file creation events where the created executable name matches a known system process (e.g., powershell.exe, svchost.exe, lsass.exe) but the target file is placed in directories outside standard Windows system locations. Naming system binaries in unexpected paths can help attackers blend into normal process naming and evade casual inspection. The detection relies on Windows file event telemetry capturing the created file path and executable filename, with exclusions for common internal Windows update/recovery and other allowed locations.
references:
  - Internal Research
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_creation_system_file.yml
author: Sander Wiebing, Tim Shelton, Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2020-05-26
modified: 2026-07-28
tags:
  - attack.stealth
  - attack.t1036.005
logsource:
  category: file_event
  product: windows
detection:
  selection:
    TargetFilename|endswith:
      - \AtBroker.exe
      - \audiodg.exe
      - \backgroundTaskHost.exe
      - \bcdedit.exe
      - \bitsadmin.exe
      - \cmdl32.exe
      - \cmstp.exe
      - \conhost.exe
      - \csrss.exe
      - \dasHost.exe
      - \dfrgui.exe
      - \dllhost.exe
      - \dwm.exe
      - \eventcreate.exe
      - \eventvwr.exe
      - \explorer.exe
      - \extrac32.exe
      - \fontdrvhost.exe
      - \fsquirt.exe
      - \ipconfig.exe
      - \iscsicli.exe
      - \iscsicpl.exe
      - \logman.exe
      - \LogonUI.exe
      - \LsaIso.exe
      - \lsass.exe
      - \lsm.exe
      - \msiexec.exe
      - \msinfo32.exe
      - \mstsc.exe
      - \nbtstat.exe
      - \odbcconf.exe
      - \powershell.exe
      - \pwsh.exe
      - \regini.exe
      - \regsvr32.exe
      - \rundll32.exe
      - \RuntimeBroker.exe
      - \schtasks.exe
      - \SearchFilterHost.exe
      - \SearchIndexer.exe
      - \SearchProtocolHost.exe
      - \SecurityHealthService.exe
      - \SecurityHealthSystray.exe
      - \services.exe
      - \ShellAppRuntime.exe
      - \sihost.exe
      - \smartscreen.exe
      - \smss.exe
      - \spoolsv.exe
      - \svchost.exe
      - \SystemSettingsBroker.exe
      - \taskhost.exe
      - \taskhostw.exe
      - \Taskmgr.exe
      - \TiWorker.exe
      - \vssadmin.exe
      - \w32tm.exe
      - \WerFault.exe
      - \WerFaultSecure.exe
      - \wermgr.exe
      - \wevtutil.exe
      - \wininit.exe
      - \winlogon.exe
      - \winrshost.exe
      - \WinRTNetMUAHostServer.exe
      - \wlanext.exe
      - \wlrmdr.exe
      - \WmiPrvSE.exe
      - \wslhost.exe
      - \WSReset.exe
      - \WUDFHost.exe
      - \WWAHost.exe
  filter_main_generic:
    TargetFilename|contains:
      - C:\$WINDOWS.~BT\
      - C:\$WinREAgent\
      - C:\Windows\SoftwareDistribution\
      - C:\Windows\System32\
      - C:\Windows\SysWOW64\
      - C:\Windows\WinSxS\
      - C:\Windows\uus\
  filter_main_tiworker:
    Image|endswith:
      - \TiWorker.exe
      - \wuaucltcore.exe
    TargetFilename|startswith: C:\Windows\Temp\
  filter_main_svchost:
    Image|endswith:
      - C:\Windows\system32\svchost.exe
      - C:\Windows\SysWOW64\svchost.exe
    TargetFilename|contains:
      - C:\Program Files\WindowsApps\
      - C:\Program Files (x86)\WindowsApps\
      - \AppData\Local\Microsoft\WindowsApps\
  filter_main_wuauclt:
    Image:
      - C:\Windows\System32\wuauclt.exe
      - C:\Windows\SysWOW64\wuauclt.exe
      - C:\Windows\UUS\arm64\wuaucltcore.exe
  filter_main_explorer:
    TargetFilename|endswith: C:\Windows\explorer.exe
  filter_main_msiexec:
    Image|endswith:
      - C:\WINDOWS\system32\msiexec.exe
      - C:\WINDOWS\SysWOW64\msiexec.exe
    TargetFilename|startswith:
      - C:\Program Files\PowerShell\7\pwsh.exe
      - C:\Program Files\PowerShell\7-preview\pwsh.exe
      - C:\Program Files\WindowsApps\Microsoft.PowerShellPreview\
  filter_main_healtray:
    TargetFilename|contains: C:\Windows\System32\SecurityHealth\
    TargetFilename|endswith: \SecurityHealthSystray.exe
    Image|endswith: \SecurityHealthSetup.exe
  filter_optional_wslhost:
    - TargetFilename: C:\Program Files\WSL\wslhost.exe
    - TargetFilename|contains|all:
        - C:\Program Files\WindowsApps\MicrosoftCorporationII.WindowsSubsystemForLinux_
        - \wslhost.exe
    - TargetFilename|contains|all:
        - C:\Users\
        - \AppData\Local\Microsoft\WindowsApps\
        - \wslhost.exe
  condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
  - System processes copied outside their default folders for testing purposes
  - Third party software naming their software with the same names as the processes mentioned here
level: medium
regression_tests_path: regression_data/rules/windows/file/file_event/file_event_win_creation_system_file/info.yml
license: DRL-1.1
related:
  - id: d5866ddf-ce8f-4aea-b28e-d96485a20d3d
    type: derived