OWASP API 5: Broken Function Level Authorization

Introduction

In the world of securing APIs, Broken Function Level Authorization takes the fifth spot in the OWASP Top 10 API Security Risks for 2023. Let’s unravel why this issue is crucial for APIs and break it down in straightforward language.

Understanding Broken Function Level Authorization in APIs:

Imagine APIs as books with various chapters, and each chapter represents a specific function or action. Broken Function Level Authorization is like letting someone access or modify chapters they shouldn’t have permission to, disrupting the orderly flow of the story.

Why It’s a Priority to Address in API Security:

Just like ensuring readers can only access or modify chapters they’re allowed to, addressing Broken Function Level Authorization is vital for APIs. It ensures that programs can only perform the functions they are authorized to, maintaining the integrity and security of the API’s operations.

Common Issues and Their Everyday Examples:

1. Reading the Entire Book (Unauthorized Data Access):
   • Broken Function Level Authorization may allow unauthorized programs to read the entire book instead of specific chapters. It’s like someone getting access to the entire story when they should only see certain parts.
2. Editing Chapters Without Permission (Unauthorized Data Modification):
   • Similar to someone editing chapters they shouldn’t, Broken Function Level Authorization could permit programs to modify data they are not authorized to change.
3. Confusing Who Can Write and Who Can Read (Access Control Flaws):
   • Broken Function Level Authorization can create confusion between who can write new chapters and who can only read. It’s like a mix-up where someone is allowed to write but shouldn’t, causing disorder in the story.

How to Fix Broken Function Level Authorization in APIs:

4. Clearly Define Function Permissions (Authorization Policies):
   • Clearly, outline who has permission to access or modify specific functions. It’s like specifying which readers are allowed to access certain chapters of the book.
5. Implement Role-Based Access Control (RBAC):
   • Use RBAC to assign roles to programs, allowing them to perform specific functions. It’s like designating different roles for readers, editors, and authors to maintain order in the storytelling.
6. Regularly Audit and Update Permissions (Ongoing Authorization Validation):
   • Consistently check and update permissions to ensure they are current and accurate. It’s like reviewing the reader list for each chapter regularly to make sure only authorized individuals can access them.
7. Use Access Tokens for Function Authorization:
   • Utilize access tokens to verify if a program has the right to perform specific functions. It’s like having a ticket that grants access to certain sections of the library.
8. Educate Developers on Proper Function Level Authorization:
   • Ensure developers understand the importance of correctly assigning function-level permissions. It’s like guiding librarians on how to manage access to different sections of the library.
9. Implement Granular Access Controls:
   • Define access controls at a granular level, specifying exactly what each program can or cannot do. It’s like providing readers with access to specific paragraphs rather than entire chapters.

Why It Matters for API Security:

Broken Function Level Authorization matters because it ensures that programs can only perform the functions they are authorized to, preventing unauthorized access or modification. It’s like maintaining a well-organized library where each reader, editor, or author has access only to the sections they are allowed to interact with.

Conclusion:

Think of APIs as books with various chapters representing different functions. Broken Function Level Authorization is like letting someone access or modify chapters they shouldn’t have permission to, disrupting the orderly flow of the story. Fixing it means clearly defining function permissions, implementing role-based access control, regularly auditing and updating permissions, using access tokens, implementing granular access controls, and educating developers on proper function-level authorization. This ensures our digital library operates smoothly with each program performing only its authorized functions, creating a secure and well-regulated storytelling environment.