SQL Server - access check cache quota

In SQL Server, the "access check cache quota" configuration option specifies the maximum amount of memory that can be used for caching access check information. This cache stores access permissions for securable objects, allowing SQL Server to validate permissions more efficiently by avoiding repeated access checks.    

Explanation 

  • Access check cache helps improve performance by reducing the overhead of permission validation when users or processes attempt to access securable objects in the database.  
  • The "access check cache quota" setting controls the maximum amount of memory that can be allocated to store access permissions in the cache.    

Security Risks 

The "access check cache quota" configuration can impact security in the following ways:    

  1. Resource Exhaustion: Allowing an excessively high cache quota may consume significant memory resources, potentially leading to resource exhaustion and impacting overall server performance.        
  2. Cache Management: Inadequate cache quota may result in cache eviction or frequent cache purging, leading to increased access check overhead and potential performance degradation.       
  3. Denial of Service: Malicious users could potentially exploit a large cache quota to exhaust memory resources, causing denial of service attacks and disrupting SQL Server operations.        
  4. Cache Poisoning: Inadequate quota management can increase the risk of cache poisoning attacks, where unauthorized access permissions are cached, leading to security vulnerabilities.    

Recommendation 

  • Configure the "access check cache quota" based on the memory resources available and the size of the access check cache needed for efficient permission validation.  
  • Regularly monitor and adjust the cache quota to balance performance optimization with security requirements.  
  • Implement security best practices, such as regularly reviewing and auditing permissions, restricting access to securable objects, and monitoring for unusual or unauthorized activities to mitigate potential security risks associated with the access check cache quota configuration.