Por Laura García/Content Manager Near BPO

In our time, data is a valuable asset for companies. Therefore, it’s very important to keep this data safe from every possible threat. In the following lines, we are going to tell you what is API security testing and why is so important for your company to implement it as a part of your processes.

When there is an error in an individual application, It’s only that individual application that fails. However, if your API fails, every application that relies on it will fail as well. This error in your platform could cost millions of dollars for your company and more than a headache for your customers.

When you expose an API to the world, many people will try to get a hold of your information, gain unauthorized access to your system, or even damage you by exploiting vulnerabilities. Also, even though APIs can fail due to other reasons, the traffic of information, while it’s being repaired, can expose sensitive data or even reveal important information about your core business. This is why is so important to ensure that your data and core systems are secure, and the best way to do that is through a security test.

The best way to perform the security test in your APIs, it’s thinking like the person that could attack your system. You have to think like that imaginary hacker that wants to access your vital information. Once you have done that, you will know all the possible attacks that could come from the outside.

In addition, according to experts on the field, the best way to target all these threats is checking one of the most important sources of information out there: the Web Hacking Incident Database (WHID). This database lists: SQL injection (18.87%), cross-site scripting (12.58%), denial of service (8.06%), predictable resource location (4.35%), unintentional information disclosure (4.35%), and brute force (4.03%) as the most probable types of security breach. Another source for security information is OWASP (owasp.org), which will help you to know the current best practices securing web-based projects.

Also, it is important to notice that these security tests are a continuous job. Even though a lot can be achieved by performing mock attacks, it is very important that your team revise regularly the best practices to secure APIs.

Best Practices to Secure APIs

No security testing is infallible, that is why is very important to implement cautionary measures to ensure the security of your data. These are the best practices to secure APIs:

  1. Use quotas and throttling: Place quotas on how often your API can be called. More calls on an API may indicate that it is being abused. It could also be a programming mistake such as calling the API in an endless loop. Make rules for throttling to protect your APIs from spikes and Denial-of-Service attacks.
  2. Know your vulnerabilities: You have to know your vulnerabilities in order to track them and be vigilant of them. You have to trace the weak spots that can be used to break the security of your APIs.
  3. Implement tokens: Assigning different tokens to every identity, helps to protect and control the access to services and resources. This is a very common practice for the financial sector.
  4. Data encryption & Data Masking: Protect your data ensuring that you and your customers use the same language. And protect your encryption by assigning signatures to your trust users. Also, whenever is possible, mask sensitive information, so it is not readable for anyone with read permissions.
  5. API Gateway: A gateway will keep track of how your APIs are being used. Also, it’s a great way to authenticate the traffic that is going through your APIs. Also, it will provide an extra layer of security by preventing direct exposure of your backend systems.

How Does APIs Security Testing Work?

The essential premise of API testing is simple, but its implementation can be hard. Here are the rules for API testing:

  1. For a given input, the API must provide the expected output.
  2. Inputs must appear within a specific range for the most part, so values outside the range must be rejected.
  3. Inputs of an incorrect type must be rejected.
  4. Any input that is null (empty), when a null is unacceptable, must be rejected.
  5. Inputs of an incorrect size must be rejected.
  6. Search your logs for sensitive information so you can place Masking techniques.


In summary, you need to test frequently any API you use to know that is safe. Also, you need to know that your APIs are working correctly. An API behaving in an expected manner is an API in less risk to be affected if attacked.

API Security Vulnerabilities

Unencrypted Data. Having their data unencrypted is one of the most common mistakes enterprises make. From a security point of view, encrypted data must be a top priority. This way, your data can travel safely from your database to the user.

APIs with No Authentication. What is more important than to know who (and how) is using your APIs? APIs authentication is pretty much fundamental if you want to have a secure API. With this step, you ensure that every movement in your APIs can be traced to the person that is performing the action. With this kind of control, you can easily spot any security breach.

CSRF Attack. In cross-site request forgery attacks, a hacker takes actions, such as transferring money or changing an email address, in an authenticated web application without the user’s knowledge.

XSS Attack. Cross site scripting attacks work by injecting a malicious script into the vulnerable application, making the user reveal his or her session cookies.

SQL Injection. An SQL injection happens when the user, instead of inputting the valid data, inputs a SQL statement that ultimately gets executed on the database. The best defense against these kinds of attacks are the framework-supported, SQL-prepared statements or using named parameters provided by ORM tools like Hibernate.

Distributed Denial of Services. This attack consists of targeting a server with a high amount of traffic with the sole purpose of making it collapse. The challenge that this attack presents is to identify and separate the regular traffic from the malign one.

In conclusion, performing an API security test is fundamental for the correct functioning of your platform. Not only are you keeping your system in prime state, you are also protecting your customers and your data from possible attacks from the outside. Testing your servers and platforms constantly is not an easy task, but in the long run, your company will save a lot of time and money by avoiding all possible threats beforehand with an adequate API Management.