Suspicious LNK Double Extension File Created

Title: Suspicious LNK Double Extension File Created
Status: test
Description:Detects the creation of files with an "LNK" as a second extension. This is sometimes used by malware as a method to abuse the fact that Windows hides the "LNK" extension by default.
References:
  -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: Nasreddine Bencherchali (Nextron Systems), frack113
Date: 2022-11-07
modified:2023-10-18
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:
  -Some tuning is required for other general purpose directories of third party apps
Level: medium