Windows Suspicious Double-Extension Execution via Parent Command Line

title: Windows Suspicious Double-Extension Execution via Parent Command Line
id: f76b98f5-da0f-4641-814a-fb4a47898dc8
related:
  - id: 1cdd9a09-06c9-4769-99ff-626e2b3991b8
    type: derived
  - id: 5e6a80c8-2d45-4633-9ef4-fa2671a39c5c
    type: derived
status: test
description: This rule flags Windows process creation where the parent image ends with document/script-like double extensions (e.g., .doc.lnk, .doc.js) or the parent command line contains those same double-extension tokens. Double extension artifacts are commonly used to disguise the true execution target and entice users to run attacker-controlled content. The detection relies on process creation telemetry, specifically the parent process image path and the parent command line content observed on the host.
references:
  - https://www.virustotal.com/gui/file/7872d8845a332dce517adae9c3389fde5313ff2fed38c2577f3b498da786db68/behavior
  - https://symantec-enterprise-blogs.security.com/blogs/threat-intelligence/bluebottle-banks-targeted-africa
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_susp_double_extension_parent.yml
author: frack113, Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2023-01-06
modified: 2023-02-28
tags:
  - attack.stealth
  - attack.t1036.007
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    - ParentImage|endswith:
        - .doc.lnk
        - .docx.lnk
        - .xls.lnk
        - .xlsx.lnk
        - .ppt.lnk
        - .pptx.lnk
        - .rtf.lnk
        - .pdf.lnk
        - .txt.lnk
        - .doc.js
        - .docx.js
        - .xls.js
        - .xlsx.js
        - .ppt.js
        - .pptx.js
        - .rtf.js
        - .pdf.js
        - .txt.js
    - ParentCommandLine|contains:
        - .doc.lnk
        - .docx.lnk
        - .xls.lnk
        - .xlsx.lnk
        - .ppt.lnk
        - .pptx.lnk
        - .rtf.lnk
        - .pdf.lnk
        - .txt.lnk
        - .doc.js
        - .docx.js
        - .xls.js
        - .xlsx.js
        - .ppt.js
        - .pptx.js
        - .rtf.js
        - .pdf.js
        - .txt.js
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1