From what I have read it seems like you have to use Solr to have PDF and Word attachments indexed and returned in a search. I have Solr working with Drupal but I think I need Tika working on Solr in order to do the document indexing. There is very little documentation I can find for Tika. Does anybody know where a good source for this is? Is there a better/easier way to have search in Drupal index attached documents?
To help you, you've this nice module Apache Solr Attachments. If you download the module you'll have a README.txt that give you some clues how to help you install and configure Tika.
We have used Search Files before with success, but I think the last time we used it was two years ago. Note that there are server side requirements for executables to do the searching, and that there isn't a Drupal 7 version available.
I discovered Search File Attachments, which has support for both Drupal 7/8 and a variety of file types.