What is the Unrecognised File Scanner and how does it work?
The Unrecognised File Scanner is a part of the Automatic WordPress File Scanner.
It identifies and eliminates all files that aren't on the WordPress Core File list.
Using the same list of official files (as from the Core File scanner) it identifies files that aren't on the list. Any non-standard files stored inside the WordPress core installation are simply in the wrong place and should be removed.
How does the Unrecognised File Scanner work?
It scans for any files in your core WordPress folders that are not part of your WordPress installation.
The Unrecognised File Scanner will scan " wp-admin" and "wp-includes" folders.
Once the scanner detects the unrecognised files, they will be flagged in Scan Results. Then, you can keep them or remove manually.
To learn more about the Unrecognised File Scanner read our blog article here.
Important: After the WordPress upgrade, the scanner could report a certain number of files as "unrecognised" but they could be part of the WordPress core installation files. For more information on this, read the article here.
How to exclude file or folder paths from scans
To do this, you can use Scan Exclusions options which is best explained in this article here.
We also highly recommend you to read A Complete Guide To The Shield Security Scans here.