MS-CFB: Microsoft Compound File Binary File Format based formats, too old and difficult to parse:
.doc - Microsoft Word 97-2003 Document
.xls - Microsoft Excel 97-2003 Document
.ppt - Microsoft PowerPoint97-2003 Document
.msi - Microsoft Windows Installer

This module detects these files as an application/x-cfb. I would like to try making it support this format.

Ref:
https://www.loc.gov/preservation/digital/formats/fdd/fdd000380.shtml - cfb
https://www.loc.gov/preservation/digital/formats/fdd/fdd000510.shtml - .xls
https://www.loc.gov/preservation/digital/formats/fdd/fdd000511.shtml - .ppt
https://www.loc.gov/preservation/digital/formats/fdd/fdd000509.shtml - .doc