API Security - Best Practices

Application Programming Interfaces(APIs) have become an integral part of the development world. API enables an application to communicate with another application. APIs are primarily used to enhance the functionality of an existing application and add more value to the end users.

However, with the rising usage of APIs, APIs have become a hotspot for security risks. It has become prone to cyber-attacks and misuse. In other words, it has become critical to take adequate security measures while handling APIs.

In this post, we will take you through some best practices that you can follow while designing an API to ensure adequate security.

Table of contents

1. Implement authentication
2. Implement authorization
3. Encrypt requests and responses
4. Establish API quotas
5. Validate all requests
6. Conduct security tests
7. Log all the activities
8. Conclusion

Implement authentication

Your APIs must perform authentication before processing any request. Authentication will try to identify the user or the program that sent the request. API authentication usually happens via a passcode, multi-factor authentication, or by authentication tokens. Usually, organizations use tokens - tokens that are sent along with the request are matched with the tokens in the database. This way, requests can be easily tracked.

OAuth protocol is a widely trusted and used API for user authentication. It also gives the administrators a portal to grant authentication tokens to third parties. Admins can set custom access rules to each token based on the API's source of the request.

Implement authorization

Once the identity of the user is authenticated, there should be a safe way to grant access to the user. And that’s where authorization helps. Put simply; authorization allows and blocks users from performing certain actions based on their authentication result. The authorization information can also be contained in the request token. REST API, in particular, must authenticate and authorize the request every time, even if the same user attempts multiple requests. This is because REST communication is stateless.

The authorization can also be based on user roles. Always follow the principle of least privilege - this way, only the essential resources can be accessed, while sensitive data can be out of bounds for users, which, in turn, eliminates the risk of sensitive data falling into the wrong hands.

Encrypt requests and responses

Man-in-the-middle attacks are quite frequent in APIs. To prevent these types of attacks, the data traveling between the user and the API should be encrypted. Even if the middleman intercepts the response or request, the data will be useless to them without the decryption method.

The encryption for REST API can be achieved using the Transport Layer Security (TLS) Protocol or Secure Socket Layer (SSL) Protocol. However, the SSL and TLS protocol only encrypts the data that is being transmitted and not the data that is sitting behind the API. As a result, this sensitive information must be encrypted in the database itself. You should use a Web Application Firewall (WAF) with SSL to prevent code injections and DDoS.

Establish API Quotas

Brute force attacks like DDoS can be prevented by imposing a limit on API calls. You can set a reasonable limit to the number of API calls the server can receive at any given time. Two main ways to limit the number of API calls are Throttling and Quotas. In throttling, once the limit is reached, the user will still be able to access the data from APIs, but the speed of response will be reduced. Quotas limit the number of API requests a user can send over time. If the number is exceeded, the user won't be given access.

Validate all requests

You must remember that API requests from even perfectly good sources might be a breeding ground for potential hackers. Always be under the impression that your data is never safe when it comes to APIs. So always have rules that will help determine if the request is legitimate, harmful, or legitimate but invalid. Having the rights rules will prevent the injection of harmful code into your application. And yes, the API request should be only processed after it passes your validation. If not, the request should be prevented from reaching the application data layer, no matter how reliable the source is.

Conduct security tests

You need to make sure that your API requests are safe and can handle any form of cyber attack. So take a good amount of time and perform sufficient security testing. During this stage, get the help of professional hackers to hack your API and get it exposed to different types of vulnerabilities. Also, testing is not a one-time process. Keep doing it at regular intervals, particularly after every API update.

Log all the activities

So far, we have seen different ways to prevent the API from getting hacked. But if the API has already been compromised, what to do? And that is where you need to have a method in place to trace the source of the issue and build a report on it. Logging all the API activity is essential. You will find it extremely useful during a breach. It will help you understand how the attackers got in. And this valuable information will help you further strengthen the security of your API.

Conclusion

While designing the API, follow the above best practices to prevent otherwise avoidable security attacks. Amping up your API security might warrant some additional effort and time, but that is well worth the effort to protect sensitive data in your server. It will help you build trust among your end users.