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In this guide, we will outline a checklist of essential steps to protect your APIs from unauthorized access or abuse, ensuring that they remain secure throughout their lifecycle.

As the world turns toward digital transformation, APIs are becoming a central part of every business since they form an ecosystem of data sharing and communication. However, managing your API security can be challenging. Gartner in 2022 predicted that APIs will become the leading attack vector, and 91% of IT professionals believe that API security should be prioritized. This only necessitates the need for developers to foster good API security practices.

In this guide, we will outline a checklist of essential steps to protect your APIs from unauthorized access or abuse, ensuring that they remain secure throughout their lifecycle.

What is API Security?

API security involves implementing measures to protect APIs from attacks and ensure that only authorized users have access to data and resources. This can include authentication and authorization protocols, encryption, rate limiting and other security measures.

Why Do You Need to Secure Your APIs?

APIs are the little doors that allow applications to share data between themselves. Without them, it would be impossible for developers or QA engineers to build any kind of application or website that could interact with other systems or third-party services like databases, cloud storage, etc.

Here’s the twist: These APIs are open to attacks which can give attackers leverage to run malicious programs with authorization. This has numerous consequences—services’ disruption, breach of user privacy and reputational damage.

So you want to ensure your APIs are secure and can be trusted by your end users, and this is exactly what API security testing helps you achieve. Most companies already understand this and have started using automated API tools to mitigate potential risks at the earliest stage.

Most Common API Security Risks

Broken Object Level Authorization (BOLA)

This is when a user has direct access to resources they shouldn’t be able to access. The most common approach involves altering an ID parameter that allows access because there aren’t enough authorization checks in place.

Broken User Authentication

Due to insufficient API authentication, attackers may use other users’ identities. This can be accomplished through credential stuffing and brute-force attacks.

Excessive Data Exposure

This occurs when an API exposes too much data which can be exploited to access other systems and private data.


This happens when harmful data is placed into a particular input field in an application.

Improper Assets Management

In the haste to release new or updated APIs, thorough documentation is sometimes skipped during API development and deployment. As a result, there are exposed endpoints and a poor grasp of how to use and implement older APIs.

Rate Limiting

Rate limiting ensures that your API can’t be abused. It limits the number of requests a user can make to your API, so you have control over how many requests per second users are allowed to make. It also helps prevent DDoS attacks and other malicious behavior on your servers by forcing them to slow down their onslaught when they exceed their quota.

Input Validation

Input validation seeks to ensure that the data input into your application is valid and follows a defined format. By validating all inputs passed to the API, you can prevent malicious attacks such as SQL injection.

Authentication and Authorization

Authentication deals with the confirmation of an identity, while authorization is the process of granting or denying access to resources. One of the key elements of API security is ensuring that only authorized users have access to the API. This can be achieved through the use of authentication and authorization mechanisms such as API keys, tokens and OAuth.

Logging and Monitoring

Logs are a critical part of the security process. They help you identify vulnerabilities, monitor your API usage, troubleshoot issues and improve performance. Insufficient logging and monitoring makes it possible for attackers to go undetected. Some manual logs are not protected against tampering and have poor design. You can tackle this by observing anomalies in logs and evaluating them for trends and patterns.

Output Encoding

To prevent cross-site scripting (XSS) attacks, it is important to encode all output from the API. This can be achieved through the use of output encoding libraries or frameworks. Output encoding prevents XSS attacks by replacing special characters with their encoded equivalents and then decoding them on the client side before they are executed.

Store Sensitive Information Correctly

Sensitive data could include usernames, passwords and other authentication tokens, credit card details or social security numbers. It’s important that you store this information on servers that are well-managed and protected against external threats.


It’s important to use Transport Layer Security (TLS) formerly known as Secure Sockets Layer (SSL) to encrypt API traffic and prevent man-in-the-middle attacks. This can be achieved by using HTTPS for all API communications.

Leverage Security Solutions

It’s important to deploy API security solutions that can tell when an authenticated user is attempting to access another user’s data without authorization. These tools can help you locate vulnerabilities in your system architecture by tracking and analyzing the number of requests that pass through each endpoint over time. They also offer DDoS attack prevention as well as authentication, authorization, encryption, anomaly detection and security. This helps strengthen your security posture and keep up with new threats.

Limit Data Exposure

There is a risk of oversharing information when an API delegates the responsibility of data filtering to the user interface rather than the endpoint. Your API security situation can be improved by making sure APIs only return the data necessary to perform the function for which they were designed and by obscuring confidential data.

Don’t Treat Security as an Afterthought

One of the best ways to ensure your APIs are secure is to design it with security in mind. This entails taking notes of potential threats, data to be protected, the intended use of the API and how it’ll interact with other systems. This includes defining rules for who can access the API, as well as what constitutes appropriate use of the API. This means everyone who uses these APIs must actively work to keep them secure.

Concluding Thoughts

Applying the API security checklist above will help you establish a baseline for a secure system and reduce the overall attack risk on your applications. Remember to keep security at the forefront of your development process, choose the right security controls and measure their effectiveness from time to time.

Test Studio can help you with automated API testing and increase your functional testing efforts regardless of testing seniority or expertise. Book your demo here.

About the Author

John Iwuozor

John Iwuozor is a freelance writer for cybersecurity and B2B SaaS brands. He has written for a host of top brands, the likes of ForbesAdvisor, Technologyadvice and Tripwire, among others. Hes an avid chess player and loves exploring new domains.


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