Database principals like the database user allow use to grant permissions on objects in a given database. Check out how to list users and find their linked logins.
SQL Server knows two types of security principals: The login or server principal and the database user or database principal. Read on to learn more about the server principal.
The Principle of Least Privilege tells us to always grant only the minimal set of permissions to any user. Read on to see what this means in the context of SQL Server.
Even if you follow security best practices to minimize the risk when setting a database to TRUSTWORTHY, if you use it to allow assemblies external access you are opening up another security hole. Read on to learn more.
Why is the TRUSTWORTHY db option so dangerous? This second post on that topic shows how that “trust” can be misused to elevate a login to be a sysadmin.