Securing SQL Server: Cross DB Ownership Chaining

Cross DB Ownership Chaining is a feature of SQL Server that allows one database to access objects in another database, even if the two databases are owned by different users. This feature is useful in certain scenarios, such as when you need to create a stored procedure that accesses objects in multiple databases.

However, Cross DB Ownership Chaining can also be a security issue if not properly managed. This is because it allows users to access objects in other databases without having to be granted explicit permissions on those objects. This can be a problem if you need to carefully control access to specific objects or if you want to prevent users from accessing sensitive data.

To mitigate the security risks associated with Cross DB Ownership Chaining, it is important to carefully manage the permissions of users who are allowed to access objects in other databases. This can be done by granting the necessary permissions only to trusted users, and by carefully reviewing the access patterns of users to ensure that they are not accessing sensitive data without proper authorization.

In addition, you can disable Cross DB Ownership Chaining on your SQL Server instance if you do not need this feature. To do this, you can use the following T-SQL command:

EXEC sp_configure 'show advanced options', 1;
RECONFIGURE;
EXEC sp_configure 'cross db ownership chaining', 0;
RECONFIGURE;

This command will disable Cross DB Ownership Chaining on your SQL Server instance, which will require users to be explicitly granted permissions on objects in other databases in order to access them.

Cross DB Ownership Chaining is a useful feature of SQL Server, but it can also be a security issue if not properly managed. It is important to carefully manage the permissions of users who are allowed to access objects in other databases, and to disable this feature if it is not needed, in order to reduce the risk of security issues.