In the ever-evolving landscape of application security, API business logic vulnerabilities have become a growing concern - especially as digital experiences rely more heavily on data-rich, interconnected services. Among the most critical and often-overlooked threats is BOLA, which stands for Broken Object Level Authorization.
What is BOLA?
BOLA is a common and dangerous business logic security vulnerability that stems from inadequate authorization checks in APIs. It occurs when an application fails to properly verify whether a user is permitted to access a specific object—such as another user’s account, file, or data record.
In simpler terms, BOLA allows attackers to gain unauthorized access to data or functions by manipulating identifiers (like user IDs, account numbers, or filenames) in API requests.
A Simple (and Scary) Example
Imagine a user is logged into a banking app and makes a legitimate API call to view their account details:
GET /mybank/account_detail/111111111
Now imagine that same user changes the account number in the request to:
GET /mybank/account_detail/222222222
If the application does not validate that the user is authorized to access account number 222222222, the system may inadvertently expose another customer’s sensitive financial data. That’s a BOLA attack.
Why It’s So Dangerous
BOLA is not only easy to exploit, but its consequences can be severe. It enables attackers—sometimes even unauthenticated users—to access data they shouldn’t see, leading to:
- Major data breaches
- Account takeovers
- Compliance violations
- Loss of customer trust
Because of its high impact and prevalence, BOLA ranks at the top of the OWASP API Security Top 10.
How to Prevent BOLA Attacks
Preventing BOLA starts with a clear principle: every API request must include a proper authorization check to ensure the requesting user has access rights to the object in question.
Key practices to mitigate BOLA risks:
- Enforce strong object-level access controls at the API gateway and business logic layers
- Test your APIs proactively using tools designed to identify broken authorization mechanisms
- Avoid relying solely on client-side logic or system obscurity for access enforcement
- Continuously map and monitor real-time API traffic to detect suspicious access patterns
- Apply runtime behavioral-based business logic enforcement to automatically block anomalous API behavior
Evolve Your Application Security
As APIs are the backbone of modern applications—especially in industries like banking, healthcare, and e-commerce—securing them against logic-based threats like BOLA is non-negotiable. Organizations must move beyond surface-level protections and invest in smarter, context-aware API security solutions.
If your APIs aren’t verifying object-level permissions at every step, it’s not a question of if a BOLA attack will occur—it’s a question of when.
What Is BOLA? | A Radware Minute