Broken Function Level Authorization - 2023 OWASP Top 10 API Security Risks

Summary

The transcript discusses broken function-level authorization, a vulnerability where users can bypass role-based access controls (RBAC) and perform actions beyond their authorized scope. It explains how admin and normal users are typically distinguished by user groups or functions, with admins having broader access. A common issue arises when endpoints designed for specific user groups (like admin endpoints) are improperly secured, allowing unauthorized access. The conversation suggests securing these endpoints by treating them as publicly exposed and applying strict function-based scopes to prevent unauthorized access, emphasizing a zero-trust approach and validating traffic consistently.

Takeaways

• 😀 Broken function-level authorization occurs when users bypass role-based access controls and access functionality outside their assigned user role.
• 😀 Most systems have user groups or roles (e.g., admin vs normal users) that determine what actions they can perform.
• 😀 Admin users typically have full access to perform operations, while normal users are restricted to a set of limited functionalities.
• 😀 This vulnerability arises when assumptions are made about where traffic comes from, often leading to improper security for endpoints.
• 😀 Admin endpoints are often exposed through specific subdomains or paths, and are assumed to be restricted, but they can be accessed improperly if not fully secured.
• 😀 A user may exploit this vulnerability by guessing the URL or endpoint meant for admins, gaining unauthorized access.
• 😀 Role-based access controls should be applied strictly to ensure sensitive operations are accessible only by authorized users.
• 😀 It's crucial not to trust traffic blindly and assume that requests will always come from trusted sources or secure environments.
• 😀 Treat sensitive endpoints, including admin endpoints, as publicly exposed, and apply the necessary validations to prevent unauthorized access.
• 😀 Implementing a zero trust approach, where all requests are treated as untrusted, helps ensure that proper security checks are always enforced.
• 😀 Strict validation of access controls and avoiding assumptions about network environments are essential to preventing this type of vulnerability.

Q & A

What is broken function-level authorization?

Broken function-level authorization is a security vulnerability where users can bypass role-based access controls (RBAC) and access or perform actions meant for other user roles, such as normal users accessing admin resources.

How are user roles typically managed in applications?

In most applications, users are assigned to different groups or roles (e.g., admin, normal user), each with specific permissions to access resources or perform certain operations based on their role.

What is the common difference between admin and normal users in terms of access?

Admin users typically have broad access, allowing them to perform nearly any operation in the system, while normal users are limited to specific, predefined actions.

How does broken function-level authorization occur in relation to admin endpoints?

This vulnerability happens when an admin endpoint, often assumed to be secure or restricted by network conditions (like a VPN), is exposed inappropriately, allowing unauthorized users to access it.

What are some common ways that attackers exploit this vulnerability?

Attackers may try to access admin-specific endpoints by guessing or discovering their URLs or subdomains, bypassing the expected access controls, and performing unauthorized actions.

Why do some applications fail to implement proper access controls on admin endpoints?

Some applications mistakenly trust the origin of traffic, assuming that requests to admin endpoints will only come from secure or internal environments, which leads to insufficient access control enforcement.

What is the solution to preventing broken function-level authorization?

The solution includes not making assumptions about the origin of traffic, treating admin endpoints as publicly exposed, and enforcing strict role-based access controls on these endpoints to ensure proper access validation.

What is the role of Zero Trust in preventing broken function-level authorization?

The Zero Trust model assumes that no request, even from within the internal network, should be trusted by default. This approach helps ensure that access control checks are always in place.

What should be done to secure admin endpoints?

Admin endpoints should be treated as publicly exposed, even if they are not directly accessible from the internet. They should be protected with robust security measures, including proper access control validation and secure traffic handling.

What role do strict role-based access controls (RBAC) play in securing endpoints?

Strict RBAC ensures that only authorized users with appropriate roles are able to access sensitive endpoints, such as those meant for admins, thereby preventing unauthorized access and minimizing security risks.