Legitimate Application Writing Files In Uncommon Location — Sigma Rule

Rule metadata and linked tags

Author: Swachchhanda Shrawan Poudel (Nextron Systems). Source status: experimental; severity: high. Source dates: 2025-12-10 / not supplied.

{
  "product": "windows",
  "category": "file_event"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 83744355b69976e8b4cfd62b1f3b993f4eee5a9aea7e2233de9564bb5a16963b

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Legitimate Application Writing Files In Uncommon Location
id: 1cf465a1-2609-4c15-9b66-c32dbe4bfd67
related:
    - id: 2ddef153-167b-4e89-86b6-757a9e65dcac # bitsadmin dedicated rule
      type: similar
status: experimental
description: |
    Detects legitimate applications writing any type of file to uncommon or suspicious locations that are not typical for application data storage or execution.
    Adversaries may leverage legitimate applications (Living off the Land Binaries - LOLBins) to drop or download malicious files to uncommon locations on the system to evade detection by security solutions.
references:
    - https://lolbas-project.github.io/#/download
author: Swachchhanda Shrawan Poudel (Nextron Systems)
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:
            # Microsoft Office Programs Dropping Executables / Rest of the apps are covered in: c7a74c80-ba5a-486e-9974-ab9e682bc5e4
            - '\eqnedt32.exe'
            - '\wordpad.exe'
            - '\wordview.exe'
            # LOLBINs that can be used to download executables
            - '\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

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://lolbas-project.github.io/#/download