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OWASP Top 10 API Security Risks – 2024

API security risks have become a huge concern for every major organization in the world as attacks on APIs by malicious attackers have increased by almost 400% in 2024. As API technology evolves, the type and number of API risks are also growing. 

Even major organizations with top-level developers and security teams often find it hard to detect all kinds of API security risks. To help organizations, Open Web Application Security Projector, or OWASP, has been researching API threats for years and has identified most of the vital API security risks that organizations should prioritize. 

Since 2019, this non-profit organization has been publishing the top 10 API security risks, and for this year, they have also come up with a list. This high-priority list is beneficial for developers and security teams, and it has been helping them develop web applications with optimum protection.

But before we dive into the OWASP Top 10 API security risks for 2024, it would be helpful to know about API security for a better understanding;

What is API Security?

API security refers to the procedures and practices employed to protect APIs against vulnerabilities and attackers. API security can also be defined as the protection of APIs, including the ones you use and the ones you own. Since APIs are nowadays widely used by organizations to connect services and share sensitive data, they have become a prime target for hackers. 

APIs serve as the primary key to the web-based interaction of applications. Exposed APIs or broken authentication and authorization in an application have become a significant issue for most data breaches that have happened in the last few years. API security helps organizations monitor and test APIs regularly to find vulnerabilities and mitigate them using best API security practices. 

With time, API security has become a pivotal aspect of web application security, and many more functions are coming to protect APIs from vulnerabilities. Previously, only basic authentication through a username and password was utilized. But in the wake of modern attacks, API security has implemented different types of security tokens like API gateways and MFA for authentication and authorization. Read our detailed blog on API security here

Now, let’s take a look at all the OWASP top API security risks;

OWASP Top 10 API Security Risk

Here is the top OWASP API security risks list that showcases all the high-priority threats that you should be aware of during 2024;

OWASP Top 10 API Security Risk

1. Broken Object Level Authorization

It is a popular API security risk where manipulation is done in the object identifier within a request to get access to data without authorization. By tweaking the identifier, malicious attackers can bypass the restriction that object-level authorization implements to reduce system exposure. 

However, this issue can be resolved by deploying authorization mechanisms at all API endpoints and functions that deal with objects from a database. Cryptographically secured random GUID values can also be utilized for creating object reference IDs.

2. Broken Authentication

OWASP has defined broken authentication as one of the top API security risks because authentication mechanisms that are not implemented correctly become victims of exploitation by attackers. It allows attackers to exploit the authentication tokens or impersonate API users’ identities temporarily or permanently to gain access to all the data. 

Credentials, passwords, keys, and tokens can be easily accessed by attackers when they gain entry. Importantly, the system won’t be able to identify the user, leading to the destabilization of overall security. Implementing rate implementation and performing detailed threat modeling can solve the broken authentication issue. Multi-factor authentication can serve as a possible solution to compromised credentials.

3. Broken Object Property Level Authorization

The broken object properly levels authorization API security risks are highlighted by OWASP, including mass assignment and excessive data exposure risks. Object property level authorization refers to mechanisms that restrict access to certain parts of an object or property. 

However, when there is a lack of authorization validation at the object property level, it leads to exploitation by unauthorized users. API endpoints with sensitive object properties can be easily modified and exploited. The best way to mitigate this issue is by validating the user’s permission at all API endpoints, and access to sensitive properties should be on a need-to-need basis.

4. Unrestricted Resource Consumption

To cater to API requests, a lot of resources are utilized, which include CPU, network bandwidth, storage, and memory. In addition, API service providers also provide biometric validation or email/SMS authentication via API integration. The service providers charge the organizations according to the number of requests the cloud application makes. 

However, attackers look for this kind of situation where the attackers cause overconsumption of resources, which leads to a Denial of Service, causing service downtime. It ultimately also increases the overall operating cost of the organization. 

Deploying minimum and maximum limits for resource usage depending on functional needs can mitigate the risk of unrestricted resource consumption. Limiting the file upload size and the number of records returned in API responses can help you diminish the use of resources.

5. Broken Function Level Authorization

Broken function level authorization is a severe API security risk highlighted by OWASP, which indicates a lack of authorization assessment in functions or controllers of API endpoints. When there is a confusing separation between regular and administrative functions or access control policies having varied groups and roles, it leads to vulnerabilities. 

Attackers can easily benefit from these risks and gain unauthorized access to various functions and users’ resources. It gets difficult for the system to implement authorization checks because of the complexities of access control policies. The best way to prevent this vulnerability is by carefully structuring API functionality and controllers that perform authentication mechanisms.

6. Unrestricted access to Sensitive Business Flows

An API becomes vulnerable when sensitive functionality is exposed in such a way that it causes harm to the business through automated overuse. This risk doesn’t usually arise from a particular implementation bug, but it can cause an exposure of business flow that attackers can abuse using automated functionality. 

Threat modeling exercises and carefully addressing excessive automated use scenarios can help businesses solve this issue. Utilizing sequencing patterns and irregular API flow detection, IP blocking, and human detection can also serve as a way to address this API security risk, but it entirely depends upon the scenario.

7. Server-Side Request Forgery

Server-side request forgery is a severe API security risk that requires a large-scale mitigation process. This vulnerability arises when an API starts accessing a remote resource through a user-supplied URL without performing any validation. In this situation, attackers have the opportunity to influence applications in various ways to send a modified outbound request to an unknown URL. 

Attackers can easily exploit the situation, even when it is protected by a firewall. Internal network calls that are usually protected by mTLS and service meshes can also be influenced by attackers. The most convenient way to overcome the issue is by assessing and sanitizing all the incoming data that is provided to the API by clients.

8. Security Misconfiguration

Security misconfiguration is a common yet serious API security issue listed by OWASP, and it is often faced by many organizations. API stacks contain complex configurations that are primarily utilized for API customization, and any misconfiguration leads to serious API security issues. 

This is mainly a result of failing to follow best security practices or a DevOps engineer having improperly configured the permission. Attackers assess the APIs to discover these configurations, and any lapse will lead to a data breach or exploitation of functionality. Frequent security updates and robust configuration management can be helpful in tackling this kind of security issue. Vulnerability management solutions from providers like CloudDefense.AI can be beneficial in automating API security.

9. Improper Inventory Management

APIs provide exposure to a lot of endpoints containing data, and due to this, it becomes imperative for organizations to make documentation and update it on a regular basis. Since most services are interconnected through APIs, it becomes an issue to maintain proper inventory management, and this lapse in management causes a lot of security risks. 

Inventory management gets much more problematic when you have multiple APIs in different cloud environments, and insufficient control leads to an increased attack surface. This provides the path for attackers to gain entry and steal all the sensitive data. However, keeping track of the API endpoints, accessibility directives, purposes, and functions can help in proper inventory management.

10. Unsafe Consumption of APIs

Another prominent API security issue on this list is the unsafe consumption of APIs where web applications receive all the data without validating and sanitizing it. Developers have a tendency to have more trust in the data the application receives from third-party APIs than user inputs. 

Thus, they don’t maintain robustness in their security standards with third-party APIs. This provides an opportunity for attackers to exploit third-party services instead of the leading API and ultimately gain access to all the sensitive data. SQL injection, deserialization attacks, external entity injection, and other attacks may be deployed by attackers. Implementing input validation with allow-lists and proper validation, as well as sanitization of data from external APIs will prove highly beneficial.


How is the OWASP Top 10 API Security List created?

The OWASP Top 10 API Security List is created through a collaborative approach where developers, security experts, and various organizations work together to determine the risks that can cause maximum impact. These entities properly analyze all the incidents and data from real-world API vulnerabilities, and depending upon the impact, they decide who should be placed in the top 10.

How can organizations use OWASP's top 10 API security list to enhance their security?

Various organizations utilize the top 10 API OWASP security lists as a guideline to assess the security posture of their APIs. By having guidance from the list, they can perform code, inventory management, penetration testing, and security audits to enhance the overall security posture.

Are the risks in OWASP's top 10 API security risk list ranked according to their severity?

The API security risks in OWASP's top 10 are ranked according to their severity, where the risk with the highest impact is listed at the top. Since the risks are ranked according to severity, it helps security teams prioritize their targets and focus on remediating the most impactful risks.

Are there tools to help secure APIs against the risks listed by OWASP's top 10 API security risks?

To cater to increasing API security risks, many tools and frameworks have been introduced that help organizations and security teams secure their APIs. Authentication and authorization, encryption tools, API gateways, and security posture management tools serve as a common choice to secure APIs against OWASP's top 10 API security risks.


The OWASP Top 10 API Security List provides a comprehensive view of the highly critical API security risks and vulnerabilities that all organizations should be aware of. This list is highly vital for developing and maintaining APIs. By monitoring these risks, organizations can quickly identify potential weaknesses in their APIs and enhance the overall security posture of their applications. This list was made after careful research by top security teams and organizations, so all organizations make these risks a high priority.

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Anshu Bansal
Anshu Bansal
Anshu Bansal, a Silicon Valley entrepreneur and venture capitalist, currently co-founds CloudDefense.AI, a cybersecurity solution with a mission to secure your business by rapidly identifying and removing critical risks in Applications and Infrastructure as Code. With a background in Amazon, Microsoft, and VMWare, they contributed to various software and security roles.
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