In today’s digital age, data security is of utmost importance for organizations. Confidential and mission-critical data should not be disclosed to unauthorized persons. As a Database Administrator (DBA), ensuring the security of data is a prime aspect of the job. In this article, we will discuss the SQL Server security model and the different features it provides for data security.
The SQL Server Security Model
The SQL Server security model consists of five layers:
- Physical security
- OS and Network security
- Database security
- Data security
- Application security
Each layer plays a crucial role in protecting the data stored in SQL Server.
Important Terms in SQL Server Security
Before diving into the details, let’s familiarize ourselves with some important terms in SQL Server security:
- Principals: These are entities that require access to SQL Server or a database. Examples include logins and roles.
- Securables: These are items that we secure or grant permissions to principals. Examples include databases, schemas, and tables.
Logins and Users
At the server level, we have logins which provide access to SQL Server. Logins can be Windows logins or SQL Server logins, depending on the authentication mechanism being used. Users are mapped to logins at the database level, and database level permissions are assigned to users.
Here’s an example of creating a login using T-SQL:
CREATE LOGIN SqlLogin WITH PASSWORD = 'Password@123';
Roles
SQL Server provides built-in roles at both the server and database level. These roles contain predefined sets of permissions. By making a login or user a member of a role, you can assign specific sets of permissions to them.
Encryption
In addition to access restrictions, it is important to encrypt critical data to ensure its security. SQL Server provides encryption mechanisms using certificates and keys. Transparent Database Encryption (TDE) is a real-time IO encryption that encrypts the database. Even if the backup or MDF file is stolen, it cannot be fully used without the certificate.
Auditing
Applying security measures is not enough; auditing is also crucial. SQL Server provides SQL Server Audit for tracking and logging events that occur at the server or database level. This includes failed login attempts, modifications in the database structure, and more. These events can be logged in the Windows event log or a file system file.
By understanding and implementing the SQL Server security model, organizations can ensure the confidentiality and integrity of their data.