This article explains what an MDW file is and how to open or convert it.
A file with the MDW file extension is a Microsoft Access Workgroup Information file, sometimes simply called a WIF (workgroup information file).
It stores the user names and passwords for users and groups that need access to a particular Access database, such as an MDB file. While the login information for a database is stored in the MDW file, it is the MDB file that contains the permissions granted to the users.
MDW files are opened with Microsoft Access.