[Boogieman]

Yes, OSQL allows you to authenticate using Windows authentication instead of normal SQL authentication, IF you are logged into the SQL server machine with a Windows account that has permission to modify the database.

So if you can gain access to an account like that on the server, you don’t actually need SQL credentials.

[Technical]

Yes, OSQL allows you to authenticate using Windows authentication instead of normal SQL authentication, IF you are logged into the SQL server machine with a Windows account that has permission to modify the database.

So if you can gain access to an account like that on the server, you don’t actually need SQL credentials.

It's not just OSQL. SQL Server by default supports Windows Authentication, and/or SQL Authentication for any client connecting to the database.

Yes - if you long on with a Windows account that has elevated privileges, then you already have that access. Executing a command under the context of that account, whether through a batch file, an application, or SSMS isn't elevating your privileges - it's what you had when you logged onto that account.