Suspicious Classes Autorun Keys Change (via registry_set)

title: Suspicious Classes Autorun Keys Change (via registry_set)
id: 2a72c617-5f42-5071-bac4-1ea4280b6176
status: stable
description: This rule detects modification of Windows Registry Classes keys used for persistence. Adversaries modify these autostart extensibility points (ASEP) to execute hostile code when file types are opened or actions are performed. Various legitimate software also uses these keys. Currently, this rule only filters out known legitimate software paths, thus it is recommended to review and tune filters for your environment to reduce false positives before deploying to production.
references:
    - https://attack.mitre.org/techniques/T1547/001/
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1547.001/T1547.001.md
    - https://learn.microsoft.com/en-us/sysinternals/downloads/autoruns
    - https://gist.github.com/GlebSukhodolskiy/0fc5fa5f482903064b448890db1eaf9d
author: Huntrule Team
date: 2026-02-01
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1547.001
logsource:
    category: registry_set
    product: windows
detection:
    selection_classes_base:
        TargetObject|contains: '\Software\Classes'
    selection_classes_target:
        TargetObject|contains:
            - '\Folder\ShellEx\ExtShellFolderViews'
            - '\Folder\ShellEx\DragDropHandlers'
            - '\Folder\Shellex\ColumnHandlers'
            - '\Filter'
            - '\Exefile\Shell\Open\Command\(Default)'
            - '\Directory\Shellex\DragDropHandlers'
            - '\Directory\Shellex\CopyHookHandlers'
            - '\CLSID\{AC757296-3522-4E11-9862-C17BE5A1767E}\Instance'
            - '\CLSID\{ABE3B9A4-257D-4B97-BD1A-294AF496222E}\Instance'
            - '\CLSID\{7ED96837-96F0-4812-B211-F13C24117ED3}\Instance'
            - '\CLSID\{083863F1-70DE-11d0-BD40-00A0C911CE86}\Instance'
            - '\Classes\AllFileSystemObjects\ShellEx\DragDropHandlers'
            - '\.exe'
            - '\.cmd'
            - '\ShellEx\PropertySheetHandlers'
            - '\ShellEx\ContextMenuHandlers'
    filter_main_drivers:
        Image: 'C:\Windows\System32\drvinst.exe'
    filter_main_empty:
        Details: '(Empty)'
    filter_main_null:
        Details:
    filter_main_svchost:
        Image: 'C:\Windows\System32\svchost.exe'
        TargetObject|contains: '\lnkfile\shellex\ContextMenuHandlers\'
    filter_optional_msoffice:
        Details: '{807583E5-5146-11D5-A672-00B0D022E945}'
    condition: all of selection_* and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium