SQL Server Security Documentation

Introduction to SQL Server Security

Securing your SQL Server environment is paramount to protecting sensitive data from unauthorized access, modification, or destruction. This section provides an overview of the security features and best practices available in SQL Server.

Effective security involves a layered approach, encompassing network security, access control, data encryption, auditing, and vulnerability management.

Key Security Concepts

• Authentication: Verifying the identity of users and applications.
• Authorization: Granting specific permissions to authenticated entities.
• Auditing: Tracking and logging security-relevant events.
• Encryption: Protecting data at rest and in transit.
• Vulnerability Assessment: Identifying and mitigating security weaknesses.
• Best Practices: Implementing recommended security configurations and policies.

Core Security Measures

Authentication Details

Windows Authentication

Leverages Active Directory for centralized security management. Highly recommended in Windows domain environments.

SQL Server Authentication

Requires users to provide a username and password directly to SQL Server. Ensure strong password policies are enforced.

Example login creation (SQL Server Authentication):

CREATE LOGIN [MyNewLogin]
WITH PASSWORD = N'aVeryStrongP@ssword123',
     DEFAULT_DATABASE = [MyDatabase],
     CHECK_EXPIRATION = ON,
     CHECK_POLICY = ON;
GO

Authorization and Permissions

Permissions are granted to logins (server-level) and users (database-level).

Database Roles

Predefined roles like db_datareader, db_datawriter, and db_owner simplify permission management. Create custom roles for fine-grained control.

Granting permissions example:

GRANT SELECT ON dbo.Customers TO PublicRole;
GO

Denying permissions example:

DENY UPDATE ON dbo.Orders TO ReadOnlyUser;
GO

Auditing and Monitoring

SQL Server Audit allows you to:

• Track successful and failed logins.
• Monitor access to sensitive tables.
• Log changes to database schemas.
• Detect potential security breaches.

Configuration involves creating a server audit, then database audit specifications.

Data Encryption

Transparent Data Encryption (TDE)

Encrypts the physical data and log files. Transparent to applications.

Always Encrypted

Encrypts sensitive data within a database column. Data is decrypted only on the client side by authorized applications. Keys are never exposed to SQL Server.

TLS/SSL Encryption

Secures data in transit between the client and server. Configure SQL Server to enforce encrypted connections.

Network Security

Firewall Configuration: Ensure only authorized IP addresses and subnets can connect to the SQL Server instance. The default port is 1433.

Disable Unused Protocols: For enhanced security, disable protocols like Named Pipes and TCP/IP if they are not required.

SQL Server Browser Service: Disable if not necessary, or restrict its access.

Regular Updates and Patching

Applying the latest Cumulative Updates (CUs) and Service Packs (SPs) is crucial to address security vulnerabilities identified by Microsoft. Regularly check the Microsoft Update Catalog and apply patches promptly.

Consider using tools like Microsoft Baseline Security Analyzer (MBSA) or Azure Security Center for vulnerability assessments.