Creation of Suspicious LNK Double Extension File (via file_event)

title: Creation of Suspicious LNK Double Extension File (via file_event)
id: 71c8d296-8180-5bd3-981f-ef9e043d6956
status: stable
description: This rule detects the creation of files with an "LNK" as a second extension. This is sometimes used by malware as a method to misuse the fact that Windows hides the "LNK" extension by default.
references:
    - https://attack.mitre.org/techniques/T1036/007/
    - https://www.crowdstrike.com/blog/meet-crowdstrikes-adversary-of-the-month-for-june-mustang-panda/
    - https://www.anomali.com/blog/china-based-apt-mustang-panda-targets-minority-groups-public-and-private-sector-organizations
    - https://www.cybereason.com/blog/research/a-bazar-of-tricks-following-team9s-development-cycles
    - https://twitter.com/malwrhunterteam/status/1235135745611960321
    - https://twitter.com/luc4m/status/1073181154126254080
author: Huntrule Team
date: 2026-01-23
tags:
    - attack.stealth
    - attack.t1036.007
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|endswith: '.lnk'
        TargetFilename|contains:
            - '.doc.'
            - '.docx.'
            - '.jpg.'
            - '.pdf.'
            - '.ppt.'
            - '.pptx.'
            - '.xls.'
            - '.xlsx.'
    filter_main_recent:
        TargetFilename|contains: '\AppData\Roaming\Microsoft\Windows\Recent\'
    filter_optional_office_recent:
        Image|endswith:
            - '\excel.exe'
            - '\powerpnt.exe'
            - '\winword.exe'
        TargetFilename|contains: '\AppData\Roaming\Microsoft\Office\Recent\'
    filter_optional_office_excel:
        Image|endswith: '\excel.exe'
        TargetFilename|contains: '\AppData\Roaming\Microsoft\Excel'
    filter_optional_office_powerpoint:
        Image|endswith: '\powerpnt.exe'
        TargetFilename|contains: '\AppData\Roaming\Microsoft\PowerPoint'
    filter_optional_office_word:
        Image|endswith: '\winword.exe'
        TargetFilename|contains: '\AppData\Roaming\Microsoft\Word'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium
regression_tests_path: regression_data/rules/windows/file/file_event/file_event_win_susp_lnk_double_extension/info.yml