Author: Kateryna Ivanenko, Invicti Brand Manager
In the ever-evolving landscape of application security, Broken Function Level Authorization (BFLA) remains one of the most overlooked yet dangerous vulnerabilities. Often categorized under access control issues, BFLA allows attackers to execute unauthorized functions within an application by bypassing insufficient or missing authorization checks. This article explores what BFLA is, how it manifests, and the practical steps to prevent it.
What Is Broken Function Level Authorization?
Broken Function Level Authorization happens when an application does not enforce proper permission checks. This allows a user to access or run certain backend functions without the required privileges.
For example, a regular user might send a request to reach admin-only features, such as deleting other users or changing roles. If the server processes that request without verifying the user’s permissions, it becomes a textbook case of BFLA.
Why Is Broken Function Level Authorization So Dangerous?
Bypasses front-end restrictions: Some developers assume hiding buttons or links in the UI is enough. But attackers can still craft requests directly.
Allows privilege escalation: Malicious users can impersonate higher-privileged roles, gaining access to critical operations or sensitive data.
Hard to detect: Without proper logging and authorization checks on every function, these attacks often go unnoticed until serious damage is done.
How to Prevent Broken Function Level Authorization
- The authorization system should follow a “deny by default” policy, granting access only through explicit permissions assigned to specific roles for each function.
- Ensuring that all administrative controllers extend from an administrative abstract controller (AbstractAdminController) that enforces authorization checks according to the user’s group or role.
- Verifying that administrative actions within standard controllers include role- and group-based authorization checks.
- Conducting regular security testing (e.g. DAST).
For instance, the Invicti platform, which brings together the capabilities of Netsparker and Acunetix, offers advanced scan configurations that allow authentication under different user accounts, helping to detect more BFLA vulnerabilities.
Conclusion
Broken Function Level Authorization is a serious yet often overlooked risk. But with consistent enforcement and proper tools, organizations can greatly reduce the chance of such exploits.
