SQL Server Analysis Services

Security in Multidimensional Modeling

Last updated: January 15, 2024

Securing your SQL Server Analysis Services (SSAS) multidimensional models is crucial for protecting sensitive data and ensuring that users only access the information they are authorized to see. SSAS provides robust security features at various levels, from the server to the cube, and even down to individual cells.

Tip: A well-defined security strategy is essential for any business intelligence solution. Plan your security roles and permissions carefully before implementing them.

Key Security Concepts

Understanding these core concepts will help you design and implement effective security for your SSAS models:

1. Roles

Roles are the primary mechanism for defining access permissions in SSAS. You create roles and assign users or Windows groups to them. Each role can be granted specific permissions on Analysis Services objects.

  • Database Permissions: Define what actions a role can perform on the entire Analysis Services database (e.g., Read, ReadDefinition, ReadAll, Process, ControlType).
  • Object Permissions: Grant permissions on specific cubes, dimensions, or mining structures.

2. Security Scope

Security can be applied at different levels:

  • Server Level: Permissions granted at the server level affect all databases on the instance. Typically reserved for administrators.
  • Database Level: Permissions granted on a specific SSAS database.
  • Cube Level: Permissions for accessing specific cubes.
  • Dimension/Hierarchy Level: Permissions for accessing specific dimensions or hierarchies within a cube.
  • Cell Level: The most granular level, allowing you to restrict access to specific data points within a cube based on user credentials or role membership.

3. Windows Authentication vs. Database Authentication

SSAS supports both Windows Authentication (using Active Directory credentials) and SQL Server Authentication. Windows Authentication is generally recommended for domain environments as it simplifies user management.

Implementing Security with Roles

The most common approach to securing multidimensional models involves creating custom roles within Visual Studio or SQL Server Management Studio (SSMS).

Creating a Role in Visual Studio

  1. Open your SSAS project in Visual Studio.
  2. In the Solution Explorer, right-click on the "Roles" folder and select "Add New Role".
  3. Give your role a descriptive name (e.g., "Sales Managers", "Marketing Analysts").
  4. Configure database permissions in the "General" tab.
  5. Navigate to the "Cube Access" tab to define permissions for individual cubes. You can grant "Read" or "Read/Write" access, or deny access entirely.
  6. In the "Dimension Data" tab, you can implement dimension security by filtering data within dimensions based on the role. This is often done using MDX expressions.
  7. For cell-level security, use the "Cell Data" tab to define restrictions based on MDX formulas.
  8. In the "Membership" tab, add Windows users or groups, or SQL Server logins, to the role.
Note: Dimension and cell security often require writing MDX (Multidimensional Expressions) queries to define the security logic dynamically.

Example: Restricting Access to a Sales Dimension

Imagine you have a "Sales Territory" dimension and you want "Regional Managers" to only see data for their respective territories.

You would create a "Regional Managers" role, assign users to it, and then configure dimension security for the "Sales Territory" dimension. The MDX expression for the filter might look something like:

IIF( USER_NAME() = "DOMAIN\Alice", "[Sales Territory].[Territory Name].&[North America]", IIF( USER_NAME() = "DOMAIN\Bob", "[Sales Territory].[Territory Name].&[Europe]", NULL -- Deny access if not Alice or Bob ) )

This example uses a simplified MDX to illustrate the concept. In practice, you'd likely join with a user-to-territory mapping table or use more complex logic.

Best Practices for SSAS Security

  • Principle of Least Privilege: Grant users only the permissions they absolutely need to perform their job functions.
  • Use Windows Groups: Manage user memberships through Active Directory groups for easier administration.
  • Document Your Roles: Maintain clear documentation of each role, its purpose, and its assigned permissions.
  • Regularly Review Permissions: Periodically audit role memberships and permissions to ensure they are still appropriate.
  • Test Thoroughly: Always test security configurations with different user accounts to verify that restrictions are working as expected.
  • Separate Administrative Roles: Create distinct roles for administrative tasks (e.g., processing, deployment) separate from data access roles.

Further Reading