Suspicious SCR File Write Event (via file_event)

title: Suspicious SCR File Write Event (via file_event)
id: 398f7655-e3c4-5660-8310-731bd86f9d16
status: stable
description: This rule detects the creation of screensaver files (.scr) outside of system folders. Adversaries may execute an application as an ".SCR" file using "rundll32.exe desk.cpl,InstallScreenSaver" for example.
references:
    - https://attack.mitre.org/techniques/T1218/011/
    - https://lolbas-project.github.io/lolbas/Libraries/Desk/
author: 'Huntrule Team'
date: 2026-05-10
tags:
    - attack.stealth
    - attack.t1218.011
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|endswith: '.scr'
    filter:
        TargetFilename|contains:
            - ':\$WINDOWS.~BT\NewOS\'
            - ':\Windows\System32\'
            - ':\Windows\SysWOW64\'
            - ':\Windows\WinSxS\'
            - ':\WUDownloadCache\'
    condition: selection and not filter
falsepositives:
    - Unknown
level: medium