In the year 2022, Twitter, now known as X, a security flaw resulted in a massive data breach. Although initially identified by Twitter’s bug bounty program, the vulnerability was exploited before it was fully patched, leading to unauthorized data exposure. The reason for this breach was Broken Object Property Level Authorization or BOPLA.
In Simple words, Broken Object Property Level Authorization refers to a security flaw in APIs that allows unauthorized users to access or modify specific properties within an object without proper permissions.
Therefore, it goes even one layer deeper than Broken Object Level Authorization). Unlike Broken Object Level Authorization, which focuses on entire objects, this vulnerability targets individual properties of objects, making it a more granular yet equally dangerous issue. This vulnerability arises when APIs fail to enforce authorization checks at the property level, enabling attackers to manipulate sensitive fields within an object.
In this blog, we’ll discuss everything about Broken Object Property Level Authorization, what causes such vulnerabilities, and how you can prevent it.
Difference Between Object-Level and Property-Level Authorization
BOLA (Broken Object Level Authorization) and BOPLA (Broken Object Property Level Authorization) are significant API security vulnerabilities. They also appear similar. But they differ in their focus.
BOLA, ranked as the top API vulnerability by OWASP API Top 10 Security Risks, occurs when an application fails to properly enforce access controls on entire objects. As a result it allows unauthorized users to access or manipulate resources/data they shouldn’t.
For example, an attacker could alter a user ID in an API request to gain access to another user’s data.
On the other hand, BOPLA targets specific properties within an object rather than the object as a whole. As a result even if an API correctly restricts access to entire objects, it may still expose sensitive data through individual properties. For instance, an attacker might exploit BOPLA to view or modify sensitive attributes like email addresses or administrative privileges within a user profile.
Thus, BOLA deals with broader object access, whereas BOPLA focuses on finer property-level permissions.
Causes of BOPLA Vulnerabilities
APIs are prone to several vulnerabilities, two of which are particularly relevant to Broken Object Property Level Authorization:
- Excessive Data Exposure: This occurs when APIs return more data than necessary in responses, potentially exposing sensitive information.
- Mass Assignment: This vulnerability allows attackers to modify multiple properties of an object through a single API call without proper validation.
How Broken Object Property Level Authorization Attacks Occur
Broken Object Property Level Authorization (BOPLA) attacks occur when an API fails to enforce proper authorization checks on individual properties within data objects, allowing unauthorized access or manipulation. This process typically begins with an attacker identifying vulnerabilities in the API through various methods, such as testing how it constructs URLs or API endpoints.
For instance, consider an API that allows users to update their profile information. If the API does not validate which properties a user can modify, an attacker could exploit this by sending a request that includes sensitive fields, such as user roles or permissions—that they should not have access to.
This manipulation often involves altering the parameters in API requests, such as changing a user ID to access another user’s data. Moreover, BOPLA can also arise from excessive data exposure, where APIs return more information than necessary. Attackers can intercept these responses and gain access to sensitive properties that should be restricted.
Let’s understand this with a couple of example scenarios:
Scenario #1: In the app code snippet shown below, the app allows a user to report other users for inappropriate behavior by allowing users to click on the Report button. When a user does that an API call gets triggered:
If you see the above code snippet carefully, the API endpoint is clearly vulnerable as it allows even unauthenticated users to access sensitive (reported) user object properties. They can view the “fullname” and “recentlocation”.
Scenario #2: This is a code snippet for a social media app that allows users to share videos, images, and text.
This is a Broken Object Property Level Authorization vulnerability where an API endpoint lacks proper property-level access controls.
While a regular user should only modify the video’s description, they can manipulate privileged properties like blocked status by simply adding them to the JSON request payload.
The API blindly accepts and processes all properties without checking if the user has permission to modify them. This could allow attackers to bypass content moderation or gain unauthorized privileges.
The fix requires implementing strict property-level access controls and whitelisting allowed properties based on user roles.
Risks of Broken Object Property Level Authorization
BOPLA can be a security hazard for organizations. Here are different types of risks and their security impacts:
| Types of Risks | Impacts |
| Excessive Data Exposure | Unauthorized access to sensitive information like account numbers, emails, and access tokens. |
| Mass Assignment | Attackers can manipulate object properties, potentially escalating privileges or altering sensitive data |
| Privilege Escalation | Unauthorized users may gain elevated permissions, allowing them to perform admin-level actions |
| Data Tampering | Attackers can modify or delete critical information, leading to data integrity issues |
| Unauthorized Transactions | Exploitation may result in unauthorized financial transactions or changes to user roles. |
| Sensitive Data Leakage | Sensitive information may inadvertently be exposed in API responses, increasing the risk of data breaches |
Consequences of BOPLA Vulnerabilities
The consequences of BOPLA vulnerability can be severe for the organizations. The lack of stringent property-level checks enables attackers to escalate privileges, view confidential data, or even take over accounts, leading to significant security breaches and compliance issues. Thus, understanding and mitigating BOPLA is crucial for maintaining robust API security.
How to Prevent Broken Object Property Level Authorization
BOPLA can be dangerous if not identified and fixed proactively. Here are some ways to prevent BOPLA attacks:
1. Implement Property-Level Access Controls
Organizations should establish clear property-level access controls that define who can access or modify specific fields within an object. This involves creating detailed authorization policies tailored to each API endpoint.
2. Use Data Validation and Whitelisting
Implementing strict data validation checks ensures that only expected properties are processed by the API. Whitelisting acceptable properties prevents unauthorized modifications.
3. Implement Selective Property Exposure
APIs should expose only the necessary data required for functionality. By minimizing the amount of sensitive information returned in responses, organizations reduce the risk of excessive data exposure.
4. Enforce Fine-Grained Access Controls
Implement fine-grained access controls that differentiate permissions for read, write, and delete actions on individual object properties. This level of granularity helps ensure that users can only perform actions they are explicitly authorized to undertake, thus minimizing potential exploitation.
Define Clear API Schemas
Establish clear schemas for your API responses and requests, specifying which properties are accessible and under what conditions. This practice helps in enforcing strict validation rules and limits exposure of sensitive data by preventing unintended data leakage.
Perform Continuous API Security Testing
Integrate continuous security testing into your development lifecycle to identify potential BOPLA vulnerabilities early on. Automated testing tools can help simulate attacks and verify that authorization checks are correctly implemented before deployment.
Conclusion
Broken Object Property Level Authorization represents a significant threat in the realm of API security. By understanding its implications and implementing robust preventive measures, organizations can safeguard sensitive data against unauthorized access and manipulation.
As APIs continue to be integral components of modern applications, prioritizing their security is essential for maintaining trust and compliance in today’s digital ecosystem.
If you’re worried about protecting your organization from such vulnerabilities, get in touch with us to know how SecureLayer7 experts can help you.
