title: Suspicious Screensaver Binary File Creation
id: 97aa2e88-555c-450d-85a6-229bcd87efb8
status: test
description: |
    Adversaries may establish persistence by executing malicious content triggered by user inactivity.
    Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1546.002/T1546.002.md
author: frack113
date: 2021-12-29
modified: 2022-11-08
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1546.002
logsource:
    product: windows
    category: file_event
detection:
    selection:
        TargetFilename|endswith: '.scr'
    filter_generic:
        Image|endswith:
            - '\Kindle.exe'
            - '\Bin\ccSvcHst.exe' # Symantec Endpoint Protection
    filter_tiworker:
        # ParentCommandLine: C:\WINDOWS\system32\svchost.exe -k DcomLaunch -p
        Image|endswith: '\TiWorker.exe'
        TargetFilename|endswith: '\uwfservicingscr.scr'
    condition: selection and not 1 of filter_*
falsepositives:
    - Unknown
level: medium

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.stealth
    - 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

title: Path To Screensaver Binary Modified
id: 67a6c006-3fbe-46a7-9074-2ba3b82c3000
status: test
description: Detects value modification of registry key containing path to binary used as screensaver.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1546.002/T1546.002.md
    - https://www.welivesecurity.com/wp-content/uploads/2017/08/eset-gazer.pdf
author: Bartlomiej Czyz @bczyz1, oscd.community
date: 2020-10-11
modified: 2021-11-27
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1546.002
logsource:
    category: registry_event
    product: windows
detection:
    selection:
        TargetObject|endswith: '\Control Panel\Desktop\SCRNSAVE.EXE' # HKEY_CURRENT_USER\Control Panel\Desktop\SCRNSAVE.EXE
    filter:
        Image|endswith:
            - '\rundll32.exe'
            - '\explorer.exe'
    condition: selection and not filter
falsepositives:
    - Legitimate modification of screensaver
level: medium