Rundll32 InstallScreenSaver Execution — Sigma Rule

Rule metadata and linked tags

Author: Christopher Peacock @securepeacock, SCYTHE @scythe_io, TactiKoolSec. Source status: test; severity: medium. Source dates: 2022-04-28 / 2023-02-09.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 28fd1ceb1afd8e720dfc58181d803eefd4be165f1e2317e02169822a2cb51c49

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: Rundll32 InstallScreenSaver Execution
id: 15bd98ea-55f4-4d37-b09a-e7caa0fa2221
status: test
description: An attacker may execute an application as a SCR File using rundll32.exe desk.cpl,InstallScreenSaver
references:
    - https://lolbas-project.github.io/lolbas/Libraries/Desk/
    - https://github.com/redcanaryco/atomic-red-team/blob/0f229c0e42bfe7ca736a14023836d65baa941ed2/atomics/T1218.011/T1218.011.md#atomic-test-13---rundll32-with-deskcpl
author: 'Christopher Peacock @securepeacock, SCYTHE @scythe_io, TactiKoolSec'
date: 2022-04-28
modified: 2023-02-09
tags:
    - attack.stealth
    - attack.t1218.011
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\rundll32.exe'
        - OriginalFileName: 'RUNDLL32.EXE'
    selection_cli:
        CommandLine|contains: 'InstallScreenSaver'
    condition: all of selection_*
falsepositives:
    - Legitimate installation of a new screensaver
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate installation of a new screensaver

Source references

• https://lolbas-project.github.io/lolbas/Libraries/Desk/
• https://github.com/redcanaryco/atomic-red-team/blob/0f229c0e42bfe7ca736a14023836d65baa941ed2/atomics/T1218.011/T1218.011.md#atomic-test-13---rundll32-with-deskcpl