Prevent Firebird database access on other server with different username/password

Question

I created a Firebird database by an account other than sysdba. If I put a copy of this db to another machine, I can open it by sysdba account and the 'masterkey' password. Thus this is real risk if some one can take a copy of it.

Is there some way to prevent this scenario?

Answer 1

The user that created a database is "just" the owner of the database, the sysdba user is administrator and is allowed to do anything to all databases on a Firebird server. This is a very good reason to never use masterkey as your password on a production server.

The usernames and passwords in Firebird 2.5 and earlier are stored in a security database (security2.fdb) that is part of the Firebird installation. So moving a database to another server (or replacing the security2.fdb) will allow "unauthorized" persons to access the database. Note that I put unauthorized in quotes here, because if a person has direct file access so they are able to make a copy of the database, or replace the security2.fdb, they have sufficient authorization on your server to do anything they want (or the security of your system has been breached).

In Firebird 3, it will be possible to store users in the database itself, but this still requires server-side configuration, so - as far as I know - this will not restrict much in this scenario. Firebird 3 will also provide support for database encryption which could allow you to only give access on a specific server, or with users that provide a specific key. Unfortunately Firebird 3 only provides the API, but not the encryption. That is left to users or library providers to implement.

There is also a trick to create a role with the name SYSDBA in your database which will prevent a user with username sysdba to connect to the database. But this is easy to circumvent by using a hex editor and some knowledge of the internal structure of a Firebird database to undo this. If the person really wants access to your data, they can also just compile a Firebird server that skips or ignores authentication.

All in all, this means that if someone has direct access to the database file, then they can create a copy and open it on another Firebird install one way or another. So the only real way to protect a database file is to make sure that users can only access the database through the Firebird server, don't have direct access to the database files and - except admins - are not able to create a backup of the database.

Even if users only have access through the server, they can still make a logical copy of the entire database structure, and all data they are allowed to access.

Consider reading Firebird File and Metadata Security