Best Practices for API Security

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When two pieces of software need to communicate with one another, they use an Application Programming Interface (API) protocol. The intermediary interface is widely used to speed up the development process by facilitating code reuse. Additionally, APIs abstract functionality between systems by isolating programs from their supporting hardware. While the advantages and practical applications of APIs continue to expand in the business world, so too do the security risks that come with using them. This is why the Open Web Application Security Project (OWASP) compiled a list of the ten most critical vulnerabilities in APIs.

This article digs into the numerous dangers posed by API flaws while teaching standard API security best practices for solid safety safeguards in place.

So, What Exactly Is API Security?

An application programming interface (API) is a collection of services that facilitates interaction between two or more software applications. By “API security,” we usually mean protecting the inner workings of a program, such as its database, user management system, and anything else that communicates with the data store.

When it comes to protecting the security of a technology stack, API security covers the use of many different methods and techniques. Both an organization’s APIs and services can benefit from a high level of security. This includes blocking bad actors from gaining access to sensitive data or performing unauthorized tasks in your name. Unfortunately, while APIs are a crucial part of modern applications, they are a common target of attackers to access sensitive information.

When working with APIs, it is essential to grasp how external applications route data. Furthermore, APIs are becoming a target of attacks. Therefore it’s important for security teams to take precautions to determine the extent of the threat and devise a strategy to mitigate it.

Risks of API Vulnerabilities

Due to their open nature, hackers frequently exploit APIs and seek valuable data such as source code, user credentials, financial details, etc. In addition, vulnerabilities in an API endpoint are also exploited by malicious actors to obtain unauthorized access to a system or network for various types of attacks, such as cross-site scripting and code injections. The top 10 vulnerabilities in web API security are recommended by risk by the Online Web Application Security Project (OWASP). Such things consist of:

Broken User Authentication – Because multi-factor authentication and credential-based logins are generally deemed unfeasible for API queries, basic authentication presents a particular difficulty with APIs. Since APIs use session tokens within the calls themselves to authenticate clients, insufficient authentication on the part of the API, such as the improper implementation of access tokens, can lead to hackers impersonating genuine users. However, if the tokens are perpetual, the attacker can stay in the system indefinitely.

Broken Object-Level Authorization – Object-level authorization is a code-level control mechanism that validates object access in APIs. An external user can swap out their resource ID for another user’s ID if the API is vulnerable at the object level due to a lack of proper authorization. Without the knowledge of the intended user, attackers can gain access to any data stored on the resource associated with the person they targeted.

Lack of Resource and Rate Limiting – When the API does not limit the quantity and frequency of requests from a given client, they might make multiple calls per second. The API consumer may request access to many records and resources all at once, placing an excessive burden on the application server. This might result in Denial-of-Service attacks because a client sending too many requests at once hampers the server’s capacity to execute requests. The lack of rate-limiting also enables hackers to conduct brute-force attacks on authentication endpoints.

Mass Assignment – The mass assignment vulnerability happens in APIs that automatically channel user input to objects or program variables. While this functionality makes code development easier, some users may initialize and overwrite server-side variables, putting the application at risk. Attackers mainly exploit this by guessing and providing additional object properties when crafting requests. They may potentially change server-side objects by reading the application’s documentation or locating vulnerable API endpoints.

Security Misconfigurations – Several security misconfigurations endanger APIs.

API Security – Best Practices to Consider

The following are some recommendations for bolstering web API security in the face of attacks:

Use rate-limiting and throttling

Throttling includes creating a temporary state that allows the API to analyze every request and is typically used as an anti-spam measure or to avoid misuse or denial-of-service attacks. The two most important factors to think about when implementing the throttling feature are how much data should be allowed per user and when the limit should be enforced.

However, rate-limiting aids in REST API administration by protecting against Denial of Service and Brute Force attacks. There are APIs whose creators have set “soft limitations,” which allow users to temporarily go above their allotted number of requests. Since timeouts can be configured to apply to either synchronous or asynchronous requests, they represent one of the simplest API security best practices. APIs that only take a certain number of requests at once may be built with the help of request queue libraries. Implementing request queues in any programming language is possible because each language has its own directory of queue libraries.

Scan for API Vulnerabilities

Enabling automated scanning, identifying vulnerabilities, and mitigating them throughout all phases of the software lifecycle is crucial for the continuing security of API services. By comparing the application’s settings to a database of known vulnerabilities, automated scanning technologies may find security flaws on their own.


Web browsers and servers may communicate securely through Transport Layer Security (TLS) and HTTPS. HTTPS is useful for protecting login credentials in transit, among other data types. When it comes to protecting data, privacy, and credibility, HTTPS implementation is a must for every API. Mutually authenticated client-side certificates offer additional security for confidential information and services and should be considered by security teams. Developers should avoid HTTP to HTTPS redirects if they care about the security of their REST API clients. Cross-Origin Resource Sharing (CORS) and JSONP queries, which are fundamentally vulnerable to cross-domain calls, should also be redirected.

Restriction on HTTP methods

The RESTful API makes it feasible for web apps to carry out many HTTP verbs. Since HTTP traffic is not encrypted, it is possible for attackers to snoop on data sent over certain HTTP protocols. It is advised that insecure HTTP methods (such as GET, PUT, DELETE, POST, and so on) be disabled. If a blanket ban is not feasible, security teams can nonetheless implement procedures to thoroughly investigate any requests that include using such techniques before allowing them. The use of HTTP methods on actions, records, and resource collections should be authenticated using the best standards for RESTful APIs.

Use adequate input validation

In theory, the authentication server might run a malicious script from untrusted users or application services. Hence the client’s data should be treated cautiously. In order to avoid this, security teams should incorporate client-side and server-side input validation techniques. Server-side validation also verifies the data supplied to prevent the many sorts of XSS and SQL Injection attacks. In contrast, client-side validation just entails interactive indication of mistakes and guidance to a user on acceptable inputs.

Use of an API gateway

In order to ensure the reliability and scalability of API services, it is helpful to have a centralized resource that can detach the client interface from the backend APIs. The API management platform also manages standard tasks like telemetry, rate restriction, and user authentication to keep services inside an organization secure. The gateway is a reverse proxy that takes API calls, coordinates the resources needed to serve them, and then provides the proper results when authentication has taken place.