Path To Screensaver Binary Modified

Hunt Hypothesis

Detects value modification of registry key containing path to binary used as screensaver.

Detection Rule

Sigma (Original)

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

KQL (Azure Sentinel)

imRegistry
| where RegistryKey endswith "\\Control Panel\\Desktop\\SCRNSAVE.EXE" and (not((ActingProcessName endswith "\\rundll32.exe" or ActingProcessName endswith "\\explorer.exe")))

Required Data Sources

False Positive Guidance

• Legitimate modification of screensaver

MITRE ATT&CK Context

• Tactic: Persistence
• Tactic: Privilege Escalation
• Technique: T1546.002 — 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
• SigmaHQ Rule