huntrule

Windows File Events: Legitimate Applications Writing Executables to Uncommon Locations

Alerts when selected Windows binaries write files to typically uncommon directories such as Temp, ProgramData, AppData, or system areas.

FreeReviewedSigma · High · v2
Product
windows
Category
file_event
Author
Swachchhanda Shrawan Poudel (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2025-12-10
Updated
2026-07-31
AnalysisDetection
title: "Windows File Events: Legitimate Applications Writing Executables to Uncommon Locations"
id: 326486f2-9fe3-4bfc-8bc3-395092df61ec
related:
  - id: 2ddef153-167b-4e89-86b6-757a9e65dcac
    type: similar
  - id: 1cf465a1-2609-4c15-9b66-c32dbe4bfd67
    type: derived
status: experimental
description: This rule flags Windows file creation events where the target process image matches known legitimate application binaries (such as common Office apps and LOLBins) and the file is written to locations that are uncommon for normal application data handling. Attackers can abuse trusted binaries to drop or download payloads into paths like Temp, ProgramData, Perflogs, AppData, or startup-related directories to blend in with routine system activity. It relies on Windows file event telemetry containing the process Image filename and the TargetFilename path.
references:
  - https://lolbas-project.github.io/#/download
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_susp_legitimate_app_dropping_in_uncommon_location.yml
author: Swachchhanda Shrawan Poudel (Nextron Systems), Huntrule Team
date: 2025-12-10
tags:
  - attack.stealth
  - attack.t1218
  - attack.command-and-control
  - attack.t1105
logsource:
  product: windows
  category: file_event
detection:
  selection_img:
    Image|endswith:
      - \eqnedt32.exe
      - \wordpad.exe
      - \wordview.exe
      - \cmdl32.exe
      - \certutil.exe
      - \certoc.exe
      - \CertReq.exe
      - \bitsadmin.exe
      - \Desktopimgdownldr.exe
      - \esentutl.exe
      - \expand.exe
      - \extrac32.exe
      - \replace.exe
      - \mshta.exe
      - \ftp.exe
      - \Ldifde.exe
      - \RdrCEF.exe
      - \hh.exe
      - \finger.exe
      - \findstr.exe
  selection_locations:
    TargetFilename|contains:
      - :\Perflogs
      - :\ProgramData\
      - :\Temp\
      - :\Users\Public\
      - :\Windows\
      - \$Recycle.Bin\
      - \AppData\Local\
      - \AppData\Roaming\
      - \Contacts\
      - \Desktop\
      - \Favorites\
      - \Favourites\
      - \inetpub\wwwroot\
      - \Music\
      - \Pictures\
      - \Start Menu\Programs\Startup\
      - \Users\Default\
      - \Videos\
  condition: all of selection_*
falsepositives:
  - Unknown
level: high
regression_tests_path: regression_data/rules/windows/file/file_event/file_event_win_susp_legitimate_app_dropping_in_uncommon_location/info.yml
license: DRL-1.1