Intranet custom CMS for random file sharing Asp.Net

Technology: Asp.Net 4.5, WebForms

Currently we have an Asp.Net web application that dynamically displays random files (.htm, .mht, .html, .pdf, .jpg, .bmp, etc...) that are composed by non programmers and shared across multiple businesses.

A dynamic menu and Iframe is used to display the documents. Iframe is resized according to it's contents. Document permissions are handled by user groups and Windows authentication. I built a SE for it as well. There is much more to this, just wanted to keep it simple for clarity.

This seems to be working ok for now. Is there a better alternative of accomplishing this using .net other than going to a full CMS system which i'm not sure would handle all of our current random documents?

NOTE: Although we have Share Point, it was not recommended for this. Wordpress was also denied for this as well.