Standard role-based authorization in .NET Core verifies whether a user can perform an action, but it often fails to check whether the user should access a specific resource. This gap leads to horizontal privilege escalation, where authenticated users can read or modify data belonging to others. The article explores how to implement resource-based authorization using .NET Core's built-in IAuthorizationService and custom handlers. It demonstrates a layered approach: first verify functional permissions (can the user call this endpoint?), then verify resource permissions (does the user own this record?). The pattern is especially relevant for multi-tenant SaaS platforms, healthcare systems, and financial applications where data isolation is critical. The author also discusses extension points, such as integrating with policy-based authorization and handling complex ownership hierarchies. For engineering teams, adopting this pattern reduces security review overhead and provides a clear, testable path to enforce data access rules consistently across the codebase.
Learn how to extend .NET Core's authorization pipeline to enforce resource-level permissions, preventing horizontal privilege escalation in data-sensitive applications.