sigmamediumHunting

ScreenSaver Registry Key Set

Detects registry key established after masqueraded .scr file execution using Rundll32 through desk.cpl

MITRE ATT&CK

defense-evasion

Detection Query

selection:
  Image|endswith: \rundll32.exe
registry:
  TargetObject|contains: \Control Panel\Desktop\SCRNSAVE.EXE
  Details|endswith: .scr
filter:
  Details|contains:
    - C:\Windows\System32\
    - C:\Windows\SysWOW64\
condition: selection and registry and not filter

Author

Jose Luis Sanchez Martinez (@Joseliyo_Jstnk)

Created

2022-05-04

Data Sources

windowsRegistry Set Events

Platforms

windows

References

Tags

attack.defense-evasionattack.t1218.011

Raw Content

title: ScreenSaver Registry Key Set
id: 40b6e656-4e11-4c0c-8772-c1cc6dae34ce
status: test
description: Detects registry key established after masqueraded .scr file execution using Rundll32 through desk.cpl
references:
    - https://twitter.com/VakninHai/status/1517027824984547329
    - https://twitter.com/pabraeken/status/998627081360695297
    - https://jstnk9.github.io/jstnk9/research/InstallScreenSaver-SCR-files
author: Jose Luis Sanchez Martinez (@Joseliyo_Jstnk)
date: 2022-05-04
modified: 2023-08-17
tags:
    - attack.defense-evasion
    - attack.t1218.011
logsource:
    product: windows
    category: registry_set
detection:
    selection:
        Image|endswith: '\rundll32.exe'
    registry:
        TargetObject|contains: '\Control Panel\Desktop\SCRNSAVE.EXE'
        Details|endswith: '.scr'
    filter:
        Details|contains:
            - 'C:\Windows\System32\'
            - 'C:\Windows\SysWOW64\'
    condition: selection and registry and not filter
falsepositives:
    - Legitimate use of screen saver
level: medium