Broken Function Level Authorization (BFLA) is a security vulnerability that is listed on the OWASP API Top 10. It allows unauthorized users to access restricted functions within an application. This can occur due to insufficient input validation, improper role-based access control, or missing authorization checks. BFLA poses significant risks, especially in APIs, as it can lead to unauthorized actions and exposure of sensitive data.
What is broken function level authorization?
Function Level Authorization (BFLA) is part of an API where the API checks the permissions, usually role-based, that a user has to a function inside of the API. This permission should be checked anytime a user uses a function to ensure that the user has the appropriate rights to the function.
Broken Function Level Authorization (BFLA) is a related vulnerability where the API fails to check the user’s permissions and to enforce proper access controls, allowing users to exploit functions they should not access. This enables unauthorized access to functions or features that should be restricted to that user. Understanding BFLA is essential for safeguarding sensitive operations and ensuring that only authorized users can perform actions within an API.
How broken function level authorization happens.
BFLA vulnerabilities occur for various reasons, including insufficient validation of user roles, missing function level access control, and improper role-based access management. For instance, if an API does not implement robust authorization mechanisms, attackers can manipulate API requests to gain access to restricted functions. They may exploit these weaknesses through techniques like API mass assignment, where they modify parameters to perform unauthorized actions, or by finding “hidden” admin-level functionalities without appropriate permissions.
Attackers can exploit BFLA vulnerabilities by substituting the ID of their resource in an API call with an ID belonging to another user. The lack of proper authorization checks enables them to access the specified resource without appropriate permissions.
What is the difference between BFLA and BOLA?
BFLA focuses on functions or actions that a user can perform, while Broken Object Level Authorization (BOLA) involves accessing, modifying, or deleting specific data entities or objects. BFLA can significantly compromise system integrity and confidentiality by allowing unauthorized users to perform actions they are not entitled to.
Broken function level authorization examples.
Examples of broken function level authorization include unauthorized users gaining access to administrative functions or making changes to data they should not be able to access. For instance, an attacker might substitute their resource ID in an API call with that of another user, allowing them to retrieve or manipulate sensitive data. Another example could be an application that allows users with lower privileges to perform actions reserved for higher-privileged users, such as deleting critical records or altering pricing data.
How broken function level authorization impacts your business.
The impacts of broken function level authorization can be severe, leading to significant financial losses, data breaches, and reputational damage. Unauthorized access can compromise sensitive business operations, allowing malicious actors to manipulate data, disrupt services, and engage in fraud. Furthermore, the consequences may extend to compliance issues, resulting in regulatory fines and legal repercussions, which can erode customer trust and damage the organization’s standing in the market.
How to prevent broken function level authorization.
The most effective way to discover BFLA vulnerabilities in an API endpoint is to identify endpoints with specific functionalities, such as login, registration, feedback, and image deletion. Analyzing the requests and responses of these endpoints can reveal weaknesses.
To mitigate BFLA vulnerabilities, organizations should implement robust authorization checks for every function or feature within their APIs. Primary defenses include:
- Authorization mechanisms: Validate that API calls are authorized for each requested action. Implementing per-request policies can help ensure compliance.
- Role-based access control: Clearly define and enforce roles to prevent unauthorized access to sensitive functions.
- Input validation: Ensure that all inputs are sanitized and validated to avoid injection attacks that could exploit authorization weaknesses.
- Regular security assessments: Conduct thorough reviews and testing of APIs to identify vulnerabilities, including penetration testing focused on function-level access.
- Security monitoring: Using an API-aware security gateway that monitors API calls in real-time to determine if the user is attempting to access functions that it should not have access to.
Read the blog post How to Mitigate API Vulnerabilities for best practices.
How Vercara can help.
Vercara’s UltraAPI solution is a purpose-built security suite designed to protect APIs and the functions and data behind them. It has 3 main components:
UltraAPI Comply monitors API traffic across the network to identify functions and the user permissions behind them. It also identifies data types, out-of-specification APIs, and compliance violations. It can help security and development teams to remediate vulnerabilities in APIs.
UltraAPI Discover actively and continuously identifies and evaluates APIs and vulnerabilities in them to detect unsafe, unprotected, and undocumented APIs.
UltraAPI Bot Manager protects APIs from cybersecurity attacks and automated bots using machine learning to fingerprint API client behavior and if that behavior is malicious or abusive.
To find out more, contact our sales team.
