Oracle Database authentication through Active Directory
This is called Enterprise User Security, which is available in Enterprise Edition databases.

You can do this with Oracle Virtual Directory or Oracle Unified Directory (preferred).

They both require the Directory Services Plus licence.

The required steps for this can be found at for example:

Enterprise User Security (EUS) with Active Directory (AD) Integration Using OUD Proxy (Doc ID 1571196.1)

A public walkthrough:

Configure EUS with OUD, AD and DB12c