Application programming interface (API) security means protecting APIs—the ones you own and those you consume—from interception, exploitation, or misuse. Their shared use is critical to software development. However, APIs pose a security risk because they enable third parties to access sensitive data or application functionality. Therefore, it’s vital to ensure that shared resources are adequately secure. 

API security must constantly evolve in response to new means of exploiting them. As a result, staying up to date on the latest API security practices is essential. 

The beginning of the new year is an excellent time to assess the present state of API security and prepare for the coming year. So, what were the most significant API security challenges in 2022, and what can you do to improve the security of your APIs in 2023? 

This article will answer those questions, but before that, it will explore some best practices for API security.

API security best practices

APIs have become increasingly popular, offering developers a way to access an application’s or service’s functionality without implementing it themselves. However, as they become more widespread, so do the security threats they face.  

If an attacker breaches an API, they could potentially access your organization’s sensitive data and compromise your API, its users, and your organization’s reputation. 

To protect these entities, you must understand the common API security vulnerabilities and how best to mitigate them.

Encryption

The basis of API security is ensuring a secure connection for data transfer between your API and users. Otherwise, third parties can intercept the data through man-in-the-middle (MITM) attacks, allowing a third party to gather, view, halt, and potentially alter the data before it reaches its destination. This attack is exceptionally consequential if the data intercepted is sensitive personal or confidential information. 

Therefore, you must adequately encrypt all data transfers from a user to the API server or vice versa. Since modern APIs use HyperText Transfer Protocol (HTTP), you can use Transport Layer Security (TLS) protocol to encrypt your API communications. 

TLS is a cryptographic protocol that provides end-to-end security for data sent between your API and its users. It secures communication by assigning both parties a public key and a private key. The public key encrypts the data, and only the private key can decrypt that data. When both parties share their public keys, they can securely transfer data. The sender (your API) uses the recipient’s public key (the user) to encrypt the data the user wants. Only the recipient’s private key can decrypt that data. 

This way, your API and its users can transmit data that only the intended parties can read, even if intruders intercept it.

Authentication

Your APIs and the resources and data they expose are important to you, your users, and cyber attackers. How do you protect these resources and ensure that only the right people can access them? The answer is API authentication. 

API authentication verifies (authenticates) the identities of those attempting to communicate with your APIs to ensure they are who they claim to be. By only allowing recognized and known users to access your APIs, you’re creating a barrier against would-be attackers.  

Now, let’s look at the most popular API authentication methods.

Basic HTTP authentication

Basic HTTP authentication is the simplest form of API authentication. It requires a client to authenticate by providing credentials, including a username and a password. The client must encode the credentials using Base64. The client provides the credentials in a header field as Authorization: Basic <credentials>. Then, it submits the encoded credentials as a single value with the username and password joined by a colon. If the value of the Authorization field matches the credentials the API has stored, the request is authorized. If not, the API rejects the request. 

Because hackers can easily decode Base64 strings, basic authentication is not a secure method, and hackers can intercept the credentials. You should use it only with other security mechanisms, such as HTTP Secure (HTTPS) over TLS.

OAuth authentication

Open authentication (OAuth) operates similarly to how a government issues a passport. With a passport, citizens can verify their identity when required because they trust the authority that issued the document. 

OAuth, like a government, validates a user’s identity before communicating with your API. The authentication service provides a token—akin to a digital passport. With the token, your API can authenticate a user’s identity because it trusts the central authority. This eases the task of user validation and is more secure than basic authentication.

API key authentication

For API authentication, a server assigns an API key—a long string of characters containing a combination of numbers and letters that serves as a unique identifier (a key) for that client. The client must include the API key in each request they make to the API. If the server recognizes the API key, it authenticates the client. If not, it rejects the request. 

Proper API authentication takes little effort to restrict access to your users’ data and API resources.

Firewalls

A firewall protects your APIs from malicious external networks and requests. It monitors the HTTP traffic to and from your APIs. Based on your predefined security rules, it determines whether to accept or reject specific requests, intercepting malicious requests before they reach the server and preventing sensitive data from leaving the network. 

You can deploy a firewall around your APIs via on-premises physical hardware (devices plugged into your APIs’ servers) or virtually in the cloud via a firewall software service. 

Deploying and maintaining up-to-date firewalls is vital to protecting your APIs from vulnerabilities.

Data validation

Inadequate input and output validation is a high-risk factor in an API function. You risk cyber attacks like SQL injections and buffer overflows if you do not set rules that specify what input values your API accepts. This practice is called schema or data validation. 

Data validation defines the allowed data types and formats of each field in your API. When a client requests your APIs, the validation process checks the content to see if it matches the schema. For example, it might stipulate that all requests contain a <user-id> field that accepts a unique ten-character string. If the API receives a request with an improper <user-id> field, it rejects the request. 

When implemented correctly, this security measure shields your APIs from accepting invalid or harmful requests that seek to insert malicious code. It also restricts what your APIs can include in the responses they send, preventing them from leaking information an attacker can use. 

Remember, your APIs should only accept and return requests with validated content.

API management

As the number of APIs and services increases, implementing authentication and other API security measures on each endpoint becomes a hectic process. Adopting proper API management tools can address this problem. 

Quality API management enables you to manage, monitor, and secure all your APIs in all environments and vendors using one platform. An API management platform like Software AG’s webMethods.io API provides security features like authentication and authorization, analytics, rate-limiting, TLS encryption, and IP filtering. These features ensure that your APIs remain adequately managed and secured without the risk of being compromised.

Monitoring

Monitoring provides insights into an API’s activity, such as request and response data, performance, and user behavior. Monitoring your APIs can help identify errors, track performance, and understand how clients are using your APIs. It can also help you diagnose and debug problems with your API. 

To this end, you should log all requests and responses, including headers, body, and parameters. It’s crucial to log everything that may be useful.

Traffic management

You’ve rolled out your API, and now people can use its capability. However, without proper traffic management, anyone can use your APIs as much as they want. This makes your API vulnerable to denial-of-service (DoS) attacks that flood your API servers with artificial requests and overload them. Ultimately, legitimate users can’t access your API, and your bill skyrockets if you’re on an expensive service plan. 

The solution is to impose proper API traffic management to control the amount of traffic your APIs receive. You can accomplish this by imposing quotas, throttling, and implementing IP address filtering.  

This way, your APIs remain safe against excessive traffic spikes and DoS attacks while allowing regular API access.

Don't share too much

It's easy for APIs to share too much information. Your API response risks exposing sensitive data to malicious third parties. To prevent this danger, remove all unnecessary information in the responses sent to users. For example, error messages may contain information that provides clues to how your APIs work, helping malicious third parties discover their vulnerabilities. Minimizing the information in your API responses is a small detail that can significantly reduce the threat of cyber attacks.

ABT—always be testing

When it comes to API security, testing is crucial. By continuously testing your APIs, you can ensure that any new vulnerabilities are immediately discovered and fixed. 

The key to properly securing your APIs is realizing that your job is never done. You will never solve the problem completely, and all the security fixes and practices in the world will never give your APIs 100 percent protection from security threats. 

You must adopt an ongoing, holistic approach to your API’s security. Since their conception, APIs have continually evolved and changed. Keep testing your security all the time to ensure there are no issues.

Most importantly—ask for help

Your API security should be the responsibility of everyone in your organization, from the developers who write the code to the Operations team who deploys it—even to the leadership team. However, modern API security is challenging, and there’s only so much you can do on your own.  

As your security needs evolve, you should seek assistance from security experts like Software AG. We can help you quickly secure your APIs. Our commercial customers in over 70 countries rely on our comprehensive API lifecycle management tools to safely deliver their APIs.

Conclusion

APIs are efficient and essential tools for sending and receiving data. As APIs evolve, so do their security vulnerabilities. However, you’re not powerless to prevent these risks. By following the API security best practices outlined in this article, you can build more secure APIs and significantly reduce the risk of vulnerabilities. You can explore these blog posts to learn more about API security on the web. 

And, for expert support, check out these API, integrations, and microservices offerings to discover how to deliver your APIs with speed, agility, and security.