Sigma rule: Suspicious ScreenSave Change by Reg.exe

Rule

Title

Suspicious ScreenSave Change by Reg.exe

Status

test

Level

medium

Author

frack113

Date

2021-08-19

Modified

2022-06-02

File

rules/windows/process_creation/proc_creation_win_reg_screensaver.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

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

Log source

product

windows

category

process_creation

Detection

selection_reg:
    Image|endswith: '\reg.exe'
    CommandLine|contains:
        - 'HKEY_CURRENT_USER\Control Panel\Desktop'
        - 'HKCU\Control Panel\Desktop'
selection_option_1: # /force Active ScreenSaveActive
    CommandLine|contains|all:
        - '/v ScreenSaveActive'
        - '/t REG_SZ'
        - '/d 1'
        - '/f'
selection_option_2: # /force  set ScreenSaveTimeout
    CommandLine|contains|all:
        - '/v ScreenSaveTimeout'
        - '/t REG_SZ'
        - '/d '
        - '/f'
selection_option_3: # /force set ScreenSaverIsSecure
    CommandLine|contains|all:
        - '/v ScreenSaverIsSecure'
        - '/t REG_SZ'
        - '/d 0'
        - '/f'
selection_option_4: # /force set a .scr
    CommandLine|contains|all:
        - '/v SCRNSAVE.EXE'
        - '/t REG_SZ'
        - '/d '
        - '.scr'
        - '/f'
condition: selection_reg and 1 of selection_option_*

False positives (as the rule lists them)

• GPO

Tags

• attack.persistence
• attack.privilege-escalation
• attack.t1546.002

MITRE ATT&CK ids this rule names

• T1546.002

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

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_reg_screensaver.yml