How to check if a file contains a file inside

[Mr.M]

Hi Dw.

How can I tell if a file contains any file within it? I mean suppose I have a picture and I want to check if its a pure picture or there is a file hidden inside, this question comes after I read this post but it was number 5 that brought this question. Here is a link: https://www.raymond.cc/blog/hide-your-secret-files-by-embedding-it-to-another-safe-source/

[Minimalist]

This link might give you some insight of how to check some common files for tempering.
http://www.forensicprotection.com/Education_Authenticate.html