How to differentiate between MSI,PUB file vs DOC/XLS/PPT files

Question

What is the correct technical way to differentiate between MSI,PUB,MSG vs DOC,XLS,PPT files. Basically all these files are of ole type and have magic header as D0 CF 11 E0 A1 B1 1A E1

Would like to know what is the correct way to find the file type for the above mentioned files from magic and submagic headers.

Thanks.

Answer 1

@GHANASHYAM SATPATHY

As you noted, you can determine from the header signature if it is a Microsoft binary file, but not the specific file type. Unfortunately, if you don’t trust the file extension, there’s no prescribed method for how to determine the file type.

Even though there is no officially endorsed way to determine the file type without the file extension, some third-party utilities have used properties that are unique and required from the Office file formats documentation to create utilities that can determine file type with a high degree of confidence. File for Windows is an open-source example that you could look at for a starting point.

Mike Bowen

Escalation Engineer Microsoft Open Specifications

Answer 2

Unfortunate to hear that there is no no prescribed method for how to determine the file type. Does the root storage CLSID can be a marker for identifying the different file type as mentioned in following:

http://fileformats.archiveteam.org/wiki/Microsoft_Compound_File

Thanks.

Answer 3

Hi @GHANASHYAM SATPATHY ,

We don't document those in the Open Specifications. It's likely they'll work, but it's not guaranteed.

Mike Bowen

Escalation Engineer Microsoft Open Specifications