Securing SQL Server

Applies to: SQL Server

Securing SQL Server can be viewed as a series of steps, involving four areas: the platform, authentication, objects (including data), and applications that access the system. This article guides you through creating and implementing an effective security plan.

You can find more information about SQL Server security at SQL Server security best practices. This includes a best practice guide and a security checklist. Be sure to install the latest service pack or cumulative update.

The platform for SQL Server includes the physical hardware and networking systems connecting clients to the database servers, and the binary files that are used to process database requests.

Best practices for physical security strictly limit access to the physical server and hardware components. For example, use locked rooms with restricted access for the database server hardware and networking devices. In addition, limit access to back up media by storing it at a secure offsite location.

Implementing physical network security starts with keeping unauthorized users off the network. For more information, see SQL Server security best practices - Infrastructure threats.

Operating system service packs and upgrades include important security enhancements. Apply all updates and upgrades to the operating system after you test them with the database applications.

Firewalls also provide effective ways to implement security. Logically, a firewall is a separator or restrictor of network traffic, which can be configured to enforce your organization's data security policy. If you use a firewall, you increase security at the operating system level by providing a chokepoint where your security measures can be focused. The following table contains more information about how to use a firewall with SQL Server.

Surface area reduction is a security measure that involves stopping or disabling unused components. Surface area reduction helps improve security by providing fewer avenues for potential attacks on a system. The key to limiting the surface area of SQL Server includes running required services that have "least privilege" by granting services and users only the appropriate rights. The following table contains more information about services and system access.

If your SQL Server system uses Internet Information Services (IIS), additional steps are required to help secure the surface of the platform. The following table contains information about SQL Server and Internet Information Services.

SQL Server uses operating system files for operation and data storage. Best practices for file security require that you restrict access to these files. The following table contains information about these files.

SQL Server service packs and upgrades provide enhanced security. To determine the latest available service pack available for SQL Server, see the SQL Server Web site.

You can use the following script to determine the service pack installed on the system.

SELECT CONVERT(char(20), SERVERPROPERTY('productlevel'));  

Principals are the individuals, groups, and processes granted access to SQL Server. "Securables" are the server, database, and objects the database contains. Each has a set of permissions that can be configured to help reduce the SQL Server surface area. The following table contains information about principals and securables.

Encryption does not solve access control problems. However, it enhances security by limiting data loss even in the rare occurrence that access controls are bypassed. For example, if the database host computer is misconfigured and a malicious user obtains sensitive data, such as credit card numbers, that stolen information might be useless if it is encrypted. The following table contains more information about encryption in SQL Server.

Certificates are software "keys" shared between two servers that enable secure communications by way of strong authentication. You can create and use certificates in SQL Server to enhance object and connection security. The following table contains information about how to use certificates with SQL Server.

SQL Server security best practices include writing secure client applications. For more information about how to help secure client applications at the networking layer, see Client Network Configuration.

Windows Defender Application Control (WDAC) prevents unauthorized code execution. WDAC is effective way to mitigate the threat of executable file-based malware. For more information, see to Windows Defender Application Control documentation.

SQL Server provides tools, utilities, views, and functions that can be used to configure and administer security.

The following table contains information about SQL Server tools and utilities that you can use to configure and administer security.

The Database Engine exposes security information in several views and functions that are optimized for performance and utility. The following table contains information about security views and functions.

• Security Considerations for a SQL Server Installation
• Security Center for SQL Server Database Engine and Azure SQL Database
• SQL Server 2012 Security Best Practices - Operational and Administrative Tasks
• Playbook for addressing common security requirements with Azure SQL Database and Azure SQL Managed Instance
• SQL Server Security Blog
• Security Best Practice and Label Security Whitepapers
• Row-Level Security
• Protecting Your SQL Server Intellectual Property