Security Administration for SQL Server

This guide provides comprehensive information on securing your SQL Server instances and databases. Effective security administration is crucial to protect sensitive data from unauthorized access, modification, or deletion.

Core Security Concepts

Understanding the fundamental security features and principles is the first step towards building a robust security posture for your SQL Server environment.

Authentication

Authentication verifies the identity of users or applications attempting to connect to SQL Server. SQL Server supports two primary authentication modes:

• Windows Authentication: Leverages Windows user accounts and groups for authentication. This is the recommended method for domain-joined environments.
• SQL Server Authentication: Uses logins and passwords specifically created within SQL Server.

Choosing the right authentication method depends on your network infrastructure and security requirements.

Authorization

Authorization determines what actions authenticated users or applications are permitted to perform within SQL Server. This is managed through server-level and database-level permissions.

• Server-Level Roles: Grant permissions on the SQL Server instance itself (e.g., sysadmin, serveradmin).
• Database-Level Roles: Grant permissions within a specific database (e.g., db_owner, db_datareader, db_datawriter).
• Object-Level Permissions: Granular control over specific database objects like tables, views, stored procedures, etc.

Implementing Security Best Practices

Adhering to security best practices is essential to minimize vulnerabilities and ensure data integrity.

Principle of Least Privilege

Grant users and applications only the minimum permissions necessary to perform their required tasks. Avoid granting broad administrative privileges unless absolutely required.

Password Policies

Enforce strong password policies for SQL Server logins, including complexity requirements, minimum length, and regular expiration.

Auditing and Monitoring

Implement auditing to track significant events, such as login attempts, permission changes, and data access. Regularly review audit logs for suspicious activity.

SQL Server Audit provides a flexible and robust mechanism for auditing server and database events. You can configure audit specifications to capture specific actions.

Encryption

Consider implementing encryption for sensitive data at rest and in transit.

• Transparent Data Encryption (TDE): Encrypts data files and log files, protecting data from being read if the physical files are stolen.
• Always Encrypted: Protects sensitive data in SQL Server databases from unauthorized access by encrypting data in client applications.
• Column-Level Encryption: Encrypts specific columns within a table.

Network Security

Secure the network communication channels used by SQL Server.

• Enable and configure SQL Server Network Configuration protocols appropriately.
• Use SSL/TLS encryption for connections to SQL Server.
• Restrict network access to SQL Server ports to authorized clients only.

Managing Security Features

SQL Server Management Studio (SSMS) provides a graphical interface for managing many security features. You can also use Transact-SQL (T-SQL) commands for more advanced configurations and automation.

Creating and Managing Logins

Use the CREATE LOGIN and ALTER LOGIN statements to manage server-level logins. For Windows Authentication, logins are managed through Active Directory.

CREATE LOGIN [MyDomain\MyUser] FROM WINDOWS;
GO

CREATE LOGIN MyLogin WITH PASSWORD = 'StrongPassword123!';
GO
            

Creating and Managing Users

Use the CREATE USER and ALTER USER statements to manage database-level users associated with logins.

USE MyDatabase;
GO

CREATE USER MyUser FOR LOGIN MyLogin;
GO
            

Granting Permissions

Use the GRANT, REVOKE, and DENY statements to manage permissions.

USE MyDatabase;
GO

GRANT SELECT ON dbo.MyTable TO MyUser;
GO

REVOKE INSERT ON dbo.MyTable TO MyUser;
GO
            

Advanced Security Topics

• Row-Level Security (RLS)
• Dynamic Data Masking
• SQL Injection Prevention
• Database Firewalling
• Security Considerations for High Availability and Disaster Recovery