Windows: Detect .SCR screen saver file creation outside common system directories

Alerts on creation of .scr screen saver files in unusual locations on Windows.

FreeReviewedSigma · Medium · v2

Product: windows
Category: file_event
Author: Christopher Peacock @securepeacock, SCYTHE @scythe_io (SigmaHQ), DRL 1.1
Published: 2022-04-27
Updated: 2026-07-31

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1218.011Rundll32
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags file creation events where the target filename ends with .scr and the file is not located in typical Windows system folders. Creating screensaver files in unusual paths can be used to stage or execute code under the screensaver file extension. It relies on Windows file event telemetry that includes the target filename for write/create operations.

Reporting behind it

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Suspicious Persistence via pcalua Launching rundll32 Control_RunDLL

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Suspicious Rundll32 Execution of Timestamp-Named DLL

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Windows: Detect .SCR screen saver file creation outside common system directories

Pivot detection · T1218.011 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-scr-screen-saver-file-created-outside-system-directories-c048f047

title: "Windows: Detect .SCR screen saver file creation outside common system directories"
id: b98685e1-19c1-47e6-8e75-3202d82d103d
status: test
description: This rule flags file creation events where the target filename ends with .scr and the file is not located in typical Windows system folders. Creating screensaver files in unusual paths can be used to stage or execute code under the screensaver file extension. It relies on Windows file event telemetry that includes the target filename for write/create operations.
references:
  - https://lolbas-project.github.io/lolbas/Libraries/Desk/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_new_scr_file.yml
author: Christopher Peacock @securepeacock, SCYTHE @scythe_io, Huntrule Team
date: 2022-04-27
modified: 2023-08-23
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:
  - The installation of new screen savers by third party software
level: medium
license: DRL-1.1
related:
  - id: c048f047-7e2a-4888-b302-55f509d4a91d
    type: derived

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