Understanding OWASP-10 for API Security

Ofer Hakimi
May 30, 2024
min to read

If you're a software developer or IT professional, you've probably heard of OWASP. The Open Web Application Security Project (OWASP) is a non-profit organization that provides tools, resources, and knowledge to help developers and organizations build more secure software.

OWASP-10 For API Security 2019

One of the most popular OWASP resources is the OWASP Top 10, a list of the ten most critical web application security risks. In 2019, OWASP released a version of the Top 10 specifically for API security. In this article, we'll explore what the OWASP-10 for API Security 2019 is, and provide some simple examples to help you understand how to protect your APIs.What is the OWASP-10 for API Security 2019?The OWASP-10 for API Security 2019 is a list of the top ten security risks that developers and organizations should be aware of when designing, building, and deploying APIs. The list was created by a team of experts from the industry, and it's based on real-world scenarios and attack patterns. The OWASP-10 for API Security 2019 covers a wide range of security risks, from authentication and access control to injection attacks and data protection. Lately in 2023 OWASP launched a new top-10 version - differences will be covered in a separated article.

The Top-10 List

- Broken Object Level Authorization

- Broken User Authentication

- Excessive Data Exposure

- Lack of Resources & Rate Limiting

- Broken Function Level Authorization

- Mass Assignment

- Security Misconfiguration

- Injection

- Improper Assets Management

- Insufficient Logging & Monitoring

Simple Examples

Let's take a look at some simple examples to illustrate some of the security risks covered in the OWASP-10 for API Security 2019 list.

Broken Object Level Authorization

Imagine you have an API that allows users to view and update their account information. However, you forgot to add proper authorization checks to make sure that only the authorized user can view and update their own account information. A malicious user could exploit this vulnerability and view or modify other users' accounts.

Broken User Authentication

In this scenario, your API uses weak authentication mechanisms, such as using plain-text passwords or not enforcing strong password policies. An attacker could easily steal a user's credentials and gain access to their account.

Excessive Data Exposure

Your API returns more information than necessary, including sensitive data such as user names and passwords. An attacker could exploit this vulnerability to steal sensitive data.

Lack Of Resources & Rate Limiting

Your API allows unlimited requests, without proper rate limiting or resource management. An attacker could launch a Denial-of-Service (DoS) attack by flooding your API with requests and causing it to become unresponsive or unavailable to legitimate users.

Broken Function Level Authorization

Your API has different functions that require different levels of authorization, but you forgot to properly enforce these authorization checks. An attacker could exploit this vulnerability to access functions they shouldn't have access to, and potentially modify or delete sensitive data.

Mass Assignment

Your API allows users to update multiple fields of an object at once, without properly validating and sanitizing the input. An attacker could exploit this vulnerability to modify fields they shouldn't have access to, or inject malicious code into the API.

Security Misconfiguration

Your API is not configured securely, leaving it vulnerable to attacks such as SQL injection, cross-site scripting (XSS), and other common web application vulnerabilities.


Your API allows user input to be executed as code, without proper input validation and sanitization. An attacker could exploit this vulnerability to execute arbitrary code on your server, potentially taking control of your entire system.

Improper Assets Management

Your API uses third-party libraries or frameworks that are not properly maintained or updated. An attacker could exploit vulnerabilities in these libraries or frameworks to gain access to your system.

Insufficient Logging & Monitoring

Your API does not log enough information or monitor for suspicious activity. This makes it difficult to detect and respond to attacks or other security incidents.


The OWASP-10 for API Security 2019 is a valuable resource for developers and organizations to understand the most critical security risks when designing, building, and deploying APIs. By familiarizing yourself with the OWASP-10

and implementing the recommended security practices, you can significantly reduce the likelihood of security breaches and protect your organization's sensitive data.

However, it is important to note that security is not a one-time task but an ongoing process that requires continuous monitoring and improvement. As new security risks emerge, it is crucial to stay updated with the latest security measures and apply them to your APIs.

In conclusion, following the OWASP-10 for API Security and adopting a proactive approach to security can help protect your organization from potential security breaches and safeguard your data and reputation.

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