Broken Object Level Authorization, often abbreviated as BOLA, is a critical API security vulnerability that can lead to unauthorized access and manipulation of sensitive data and resources. A BOLA occurs when an application fails to implement proper access controls for individual objects or resources. In web applications, objects can refer to data records or specific functionalities available to users.
When an application suffers from Broken Object Level Authorization, it allows unauthorized users to access, modify, or delete sensitive data or perform actions they shouldn't be able to. This vulnerability arises when an application does not adequately verify whether a user is authorized to access or manipulate a specific object based on their role, permissions, or ownership of the object in question.
BOLA vulnerabilities, also known as IDOR., can have serious consequences, enabling malicious actors to manipulate or access unauthorized resources or data within the application. For instance, a BOLA vulnerability in a web application that permits users to view only their own data records could allow an attacker to access records belonging to other users. Similarly, an application that restricts certain functionalities to authorized users could be circumvented by a BOLA attack, granting unauthorized access to those functionalities.
To mitigate the risk of Broken Object Level Authorization, developers must ensure that proper access controls are implemented on all levels of their applications. This involves verifying a user's permissions and roles before granting them access to a particular object or resource. Additionally, the use of indirect object references and access control enforcement mechanisms, such as attribute-based access control (ABAC) or role-based access control (RBAC), can further enhance an application's security posture.
Example of BOLA vulnerability
Let's consider a hypothetical online banking application as an example to illustrate Broken Object Level Authorization (BOLA). In this scenario, each user can access their bank account information and perform various actions, such as checking their balance, reviewing transaction history, or transferring funds.
Suppose the application uses a direct object reference to identify each user's account information, such as a URL containing the account number:
In this case, user 123456 can access their account information by visiting the URL. However, if the application does not implement proper object-level authorization, a malicious user could exploit this vulnerability by simply changing the account number in the URL:
By doing so, the attacker gains unauthorized access to another user's account information, potentially viewing sensitive data or performing unauthorized actions, such as transferring funds.
How to prevent BOLA vulnerabilities
To prevent Broken Object Level Authorization vulnerabilities, developers should implement robust access control checks to verify that the user requesting access to a specific account has the necessary permissions or ownership. One solution could involve using indirect object references, such as mapping account numbers to unique session identifiers so that users cannot access other accounts by manipulating the URL directly. Additionally, proper access control mechanisms, such as role-based access control (RBAC) or attribute-based access control (ABAC), should be in place to ensure that users can only access and manipulate the objects they are authorized to interact with.
Detecting and mitigating BOLA vulnerabilities can be challenging, as they may not be immediately evident to users or developers. Therefore, it is crucial to implement effective access controls and regularly test for potential vulnerabilities in web applications in order to prevent BOLA attacks.
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