API Security: 12 Best Practices

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An application programming interface (API) is a set of rules and specifications that govern how two applications can interact, usually over the internet. API is also known as an application’s “front door.” It enhances the development ecosystem by making it easier to build on top of existing platforms instead of starting from scratch.

For example, developers working on a travel app can use API functionality to call-in data from a weather app rather than having to develop their own weather data functionality. They can also import pricing information and availability from hotels and airlines.

APIs have become increasingly popular as enterprises strive to provide their customers with a better user experience by assembling best-of-breed software components. However, this increased popularity has also made APIs a prime target for cyber criminals.

This guide will discuss the most critical API security vulnerabilities and provide 12 ways enterprises can secure their APIs.

Also read: Fighting API Sprawl in the Modern Cloud Maul

Importance of API Security

API security is essential to enterprises because APIs are often used to connect disparate systems and share data. This data may include sensitive information such as financial data, personal information, or health records. As a result, API security vulnerabilities can lead to data breaches, theft of customer information, or loss of business reputation.

API security is also crucial because APIs are often used to expose internal systems and data to external developers. This is done for various reasons, such as enabling partner integration or providing a way for third-party developers to build new features on top of an existing platform.

However, exposing internal systems and data to external developers also comes with risks. For example, if an API is not secured correctly, it may allow unauthorized access to sensitive data. In addition, cybercriminals can also exploit API security vulnerabilities to launch denial-of-service (DoS) attacks or take over accounts.

The Most Critical API Security Vulnerabilities

Broken object-level authorization (BOLA)

BOLA is a common vulnerability that affects API-based applications. It occurs when there is incorrect exposure of sensitive fields within an object.

A good example is where a user’s personal information isn’t securely stored in an API response sent to their browser or mobile device. As a result, attackers can misuse it to impersonate the real user and gain access to their account.

Broken user authentication

When a system’s credentials aren’t necessary for an API request, it’s most likely a broken user authentication problem. This vulnerability is critical since the incorrect implementation of the authentication procedure might enable unauthorized access to critical information and systems.

Lack of resources and rate limiting

API servers can be overloaded by malicious requests that consume all available resources. This can lead to a denial of service for legitimate users. API rate limiting is a technique used to control the amount of traffic that an API server can handle. It helps to protect against DoS attacks and ensures the API is available for legitimate users.

Improper asset management

API keys and secrets are often used to authenticate API requests. If these API keys and secrets are not correctly managed, they can be leaked and used by attackers to gain unauthorized access to API resources.

Excessive data exposure

API responses often include sensitive data such as user information, financial data, or health records. If too many API endpoints return sensitive data, it can increase the chances this data will be leaked.

Mass assignment

Mass assignment is a vulnerability when an API endpoint accepts requests containing too many parameters. Attackers can exploit this to modify data they should not have access to.

Broken function-level authorization

API endpoints often have different access levels, depending on the user’s role. For example, an administrator might have access to all API endpoints, while a regular user might only have access to some of them. If an API endpoint does not correctly check the user’s permissions, it can allow unauthorized access.


API endpoints are often vulnerable to SQL injection and script injection attacks. Criminals can use these attacks to gain access to sensitive data or execute malicious code on the server.

12 Best Practices to Secure APIs

Despite the risks, there are steps that enterprises can take to secure their APIs.

  1. Implement Authentication and Authorization with OAuth: API authentication is the process of verifying authorized users make API requests, while authorization is the process of verifying API requests are made with the correct permissions. These two processes can be implemented via OAuth to prevent unauthorized access to resources.
  2. Encryption: API requests and responses can be encrypted to protect sensitive data from being leaked. SSL/TLS encryption can be used to encrypt API traffic as well as API keys to prevent them from being leaked.
  3. The Principle of Least Privilege: The principle of least privilege states that users should only have access to the resources they need to perform their job. This can be applied to endpoints by ensuring each API endpoint has the minimum amount of required access.
  4. Limit Data Exposure: API responses should only return the necessary data. API endpoints that return sensitive data should be restricted to authorized users.
  5. Enforcing Rate Limiting: API rate limiting is a technique used to control the amount of traffic an API server can handle. It helps to protect against DoS attacks and ensures the API is available for legitimate users.
  6. Validating API Inputs: API input validation verifies that API requests contain valid data, which can help to prevent malicious requests from being processed by the server.
  7. Proper Management of API Keys and Secrets: An API key is essentially a user’s ID, and the API secret is a “password” or code used to validate that ID. An API key and secret should only be shared with authorized users.
  8. Monitoring API Traffic: API traffic monitoring is the process of monitoring API requests to detect malicious activity.
  9. Logging API Activity: API activity logging is the process of recording API requests and responses. This can help to detect malicious activity and diagnose problems.
  10. Updating APIs Regularly: It is vital to keep API software up to date to address security vulnerabilities.
  11. Adopt a Zero Trust Philosophy: In zero trust, all API requests should be treated as untrusted. This principle can be applied by implementing authentication and authorization for all API requests.
  12. Using API Management Solutions: API management tools and platforms help secure APIs by providing authentication, authorization, rate limiting, and traffic monitoring in a secure environment. In addition, these tools act as an interface between your business and developers. They let you decide what clients can access, establish usage restrictions for each API, monitor who uses them the most frequently and how, regulate security measures such as OAuth or IP restrictions, and more.

What Lies Ahead?

With the massive growth of microservices, the pressure on developers to build applications faster, and the coming ubiquity of IoT devices, API will continue to grow with a commensurate rise in API security concerns.

API management solutions will become more sophisticated and easier to use, making them more widely adopted. As new threats emerge, best practices for API security will continue to evolve. So, enterprises need to be regularly aware of the latest API security news and trends to keep their applications safe.

Read next: Best Unified Endpoint Management (UEM) Software 

Kihara Kimachia
Kihara Kimachia
Kihara Kimachia is a writer and digital marketing consultant with over a decade of experience covering issues in emerging technology and innovation. In addition to appearing regularly in Enterprise Networking Planet, his work has been published in many leading technology publications, including TechRepublic, eSecurity Planet, Server Watch, Channel Insider, IT Business Edge, and Enterprise Storage Forum.

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