SQL Server Analysis Services Security
This section provides comprehensive documentation on securing your SQL Server Analysis Services (SSAS) solutions. Effective security is crucial for protecting sensitive data within your multidimensional and tabular models.
Key Security Concepts
Understanding the following concepts is fundamental to implementing robust security in SSAS:
- Authentication: Verifying the identity of users or applications attempting to access SSAS. SSAS supports Windows authentication and SQL Server authentication.
- Authorization: Determining what actions an authenticated user or application is permitted to perform and what data they can access. This is typically managed through roles and permissions.
- Roles: Collections of permissions that can be assigned to users or groups. SSAS allows for database roles, object-level roles (for multidimensional models), and cell-level security.
- Permissions: Specific rights granted to a role, such as Read, Read Definition, Read Security, Process Full, Process Add, etc.
- Row-Level Security (RLS): Restricting access to specific rows within a table based on user identity. This is primarily applicable to tabular models.
- Cell-Level Security (CLS): Restricting access to individual cells within a multidimensional cube.
Implementing Security in SSAS
Follow these steps to implement effective security measures:
1. Database Roles
Database roles provide a foundational layer of security at the database level. Common roles include:
- Administrator: Full control over the Analysis Services instance and all its databases.
- Database Administrator: Full control over a specific Analysis Services database.
- Read: Allows users to connect to the database and browse data.
- Read Definition: Allows users to view metadata (schemas, structures) but not data.
You can create and manage database roles using SQL Server Management Studio (SSMS) or Tabular Editor.
2. Multidimensional Model Security (Cubes)
For multidimensional models, you can define security at various levels:
- Object-Level Security: Restrict access to specific dimensions, hierarchies, attributes, and measures. This is defined within cube or dimension properties.
- Cell-Level Security: Create security cells to restrict access to specific data points within the cube based on user roles and dimension attribute values. This is configured using MDX expressions.
3. Tabular Model Security
Tabular models offer a more streamlined approach to security:
- Table-Level Security: While not a direct permission, row-level security effectively controls access to data at the table level.
- Row-Level Security (RLS): Define filter expressions (DAX) that limit the rows visible to users based on their role membership. This is managed within the model in tools like Visual Studio or Power BI Desktop.
4. Permissions Management
Assign users and Windows groups to the appropriate roles within SSAS. Best practice is to assign permissions to Windows groups rather than individual users, simplifying management.
Tools for Security Management
- SQL Server Management Studio (SSMS): The primary tool for managing SSAS security, including roles, permissions, and server-level settings.
- Visual Studio (with Analysis Services projects): Used for designing and deploying multidimensional and tabular models, including initial security configurations.
- Tabular Editor: A powerful third-party tool for advanced management of tabular models, including security definitions.
- Power BI Desktop: For developing tabular models intended for Power BI, security is configured directly within the model.
Best Practices for SSAS Security
- Use Windows authentication whenever possible.
- Leverage Windows groups for role assignments.
- Implement the principle of least privilege.
- Regularly review and audit security settings.
- Secure the SSAS instance itself with appropriate firewall rules and access controls.
- For tabular models, utilize row-level security extensively.
- For multidimensional models, carefully design object-level and cell-level security.