OWASP API Top 10: The Essential Guide to Securing APIs

Here’s an overview of the OWASP API Top 10 for 2025:

1. API1:2023 – Broken Object Level Authorization

Broken Object Level Authorization (BOLA) occurs when APIs allow unauthorized access to sensitive data or operations by failing to enforce proper access controls. Attackers can manipulate input parameters, like object IDs, to access resources they shouldn't be able to. To prevent this, developers should ensure that all objects are validated for user access rights.

2. API2:2023 – Broken Authentication

Broken authentication happens when APIs don't correctly validate users’ identities or fail to securely manage session tokens. This can allow attackers to impersonate legitimate users. Implementing robust multi-factor authentication (MFA) and session management practices can mitigate these risks.

3. API3:2023 – Excessive Data Exposure

APIs often return more data than necessary, potentially exposing sensitive information to unauthorized users. Attackers can exploit this overexposure to gather valuable data. Developers should adhere to the principle of least privilege, ensuring that APIs only return data relevant to the user's role or request.

4. API4:2023 – Lack of Resources & Rate Limiting

APIs that fail to implement proper rate limiting can become targets for Denial of Service (DoS) attacks, where malicious actors flood the system with excessive requests. To prevent this, APIs should include mechanisms to limit the number of requests from a user or client in a given time frame.

5. API5:2023 – Broken Function Level Authorization

In APIs, different endpoints often require different levels of user permissions. Broken function-level authorization occurs when APIs do not properly enforce these permissions, allowing users to access functions they should not be able to. This can be prevented by thoroughly validating user roles and permissions for each API function.

6. API6:2023 – Mass Assignment

Mass Assignment happens when an API allows a user to update fields that they shouldn’t be able to access. For example, a user could update the "role" or "account balance" fields of their profile if not properly restricted. Developers should use an allowlist to control which fields can be updated by the user.

7. API7:2023 – Security Misconfiguration

Security misconfiguration happens when APIs or their environments are not securely configured. This could be the result of default settings, incomplete configurations, or exposing unnecessary services. Regular security audits and configuration reviews are essential to minimizing these risks.

8. API8:2023 – Injection

API injection attacks, such as SQL or NoSQL injection, occur when an API fails to properly validate or sanitize user input. Attackers can exploit this vulnerability to run malicious code in the database or the backend system. Developers should always sanitize user inputs and use parameterized queries to prevent injection attacks.

9. API9:2023 – Improper Assets Management

Improper asset management occurs when an API exposes endpoints, services, or information that should be restricted. This could include versioned APIs that are no longer in use or left unsecured. API version control and proper documentation are key to preventing the exposure of obsolete or sensitive resources.

10. API10:2023 – Insufficient Logging & Monitoring

Without proper logging and monitoring, it becomes difficult to detect and respond to security breaches. APIs should log events like failed authentication attempts, unusual data access patterns, or other suspicious activities. Regular monitoring and automated alerts help identify and mitigate attacks in real-time.

Conclusion

The OWASP API Top 10 provides a critical framework for understanding the most common security threats to APIs and how to address them. By incorporating these best practices into API design, development, and maintenance, organizations can significantly reduce their risk of breaches and attacks. Regular security assessments, a strong focus on access control, and staying up to date with evolving security threats are essential steps for keeping APIs safe in today’s rapidly changing digital landscape.