API Security Threats & How To Protect Against Them

APIs, or Application Programming Interfaces, are sets of rules and protocols that enable software applications to communicate with each other. They define the methods and data formats software programs can use when communicating with other software programs. 

APIs have become essential in the digital ecosystem because of the risk of service-oriented architecture, microservices, and the need to integrate and communicate with different software systems. APIs play a vital role in business today and our interconnected digital environment.

However, APIs are facing increasing threats, leading to potential data breaches, service disruptions, and other security incidents. The ubiquitous use of APIs in business further exacerbates these threats, as they’re attractive targets for cybercriminals.

Here’s all you need to know about protecting APIs from threats, why it matters, and critical best practices to keep your data safe. 

Understanding API threats: why API security is important

With the evolution of the API ecosystem, API misuse and abuses by bad actors have become one of the most common sources of cyberattacks today. Your organization needs to be vigilant against attacks to reduce and mitigate any damage that may result from one. 

Over the past few years, APIs have become the key target for malicious attacks. A quick look at the stats quickly reveals how API threats are evolving:

The Open Web Application Security Project (OWASP) is a non-profit community dedicated to helping organizations maintain trusted web applications and APIs. Although the community is well-known for its OWASP Top 10 list for web applications, they also released a Top 10 API Security Threats in 2023 that outlines the most significant and common API vulnerabilities organizations face:

  1. Broken object-level authorization
  2. Broken authentication
  3. Broken object property level authorization
  4. Unrestricted resource consumption
  5. Broken function level authorization
  6. Server-side request forgery
  7. Security misconfiguration
  8. Lack of protection from automated threats
  9. Improper inventory management
  10. Unsafe consumption of APIs

API security

The modern digital world relies heavily on APIs to conduct business. Organizations use APIs to transfer critical data and connect services. API threat protection is an essential component of any organization’s cybersecurity strategy. Their protection is paramount, considering the sensitive data APIs handle and transmit. Any compromise can lead to data breaches, severe financial implications, reputational damage, and broken customer trust.

Because APIs connect critical systems and application parts, a breach can result in severe system disruption or unauthorized system control. Properly protecting APIs means you are:

  • Maintaining your system integrity (and probably data integrity, too).
  • Ensuring continuous and reliable operations.

The importance of API threat protection is multifaceted, contributing to data protection, system integrity, regulatory compliance, and maintaining customer trust. Given the potential high costs associated with reactive responses to breaches, proactive investments in API threat protection are highly economical in the long run.

(Learn how to test the security of APIs.)

Best practices to protect APIs from threats 

No tool can guarantee API security, but an integrative, proactive approach to threats will provide your API the protection it needs against cyber criminals. Here are some of the best practices for API threat protection.

Implement robust authentication and authorization

Secure APIs must have a strong authentication and authorization system — period. This will help you manage access control and keep potential attacks at bay. Some critical ways to manage access to your API include:

OAuth 2.0. OAuth 2.0 works by allotting user authentication to the service hosting the user account and authorizing account access to third-party applications. While OAuth 2.1 is currently underway, OAuth 2.0 continues to be the standard authorization protocol.

OpenID Connect. OpenID Connect is built on top of the OAuth 2.0 protocol. It offers a simple identity layer that allows apps to verify end-users through the authentication performed by an Authorization Server. Clients can receive ID tokens in addition to access tokens, providing detailed information about the user. 

JSON Web Token (JWT). JWT is a JSON-based open standard that creates access tokens based on the number of claims. For example, your server could generate one token with the claim “logged in as admin” and give it to your client. Your client can then use the token to prove it’s logged in as admin.

Security Assertion Markup Language (SAML). SAML is a data format that exchanges authentication and authorization data among parties. It’s typically used among identity providers and service providers for single sign-on (SSO) solutions.

API Keys. An API key is a token your client provides when making API calls. It’s a simple method but valuable when combined with other security measures.

Role-Based Access Control (RBAC). In RBAC, permissions are linked with user roles, and users are assigned according to their roles. Many use RBAC to simplify managing each user’s permission while still ensuring each has the appropriate access needed to perform their tasks.

(Learn all about the differences between ABAC and RBAC.)

Mutual TLS (mTLS). Sometimes called two-way TLS, mTLS is especially useful in server-to-server communication. The server and client must authenticate each other with validating digital certificates before data transfer begins.

Two-Factor Authentication (2FA). 2FA provides an additional layer of security by requiring users to use two separate authentication methods. This could be something the user knows (such as a password), something they have (such as a mobile device), or something they are (such as a fingerprint).

Use rate limiting

Rate limiting is a technique that limits your API traffic. It limits how many requests your client can make to your API in a set timeframe. For example, you might limit requests to 1000 per user per hour.

Rate limiting is crucial for many reasons. One of the most significant is that it helps prevent Denial-of-Service (DoS) attacks. If an attacker tries to overwhelm your API with a flood of requests, rate limiting will protect your system by only allowing a set number of requests per client. It also helps you better control the load on your server to prevent it from becoming overloaded. Sometimes, users misuse or overuse an API, whether it’s for creating spam, data scraping, or brute force login attempt. Rate limiting helps prevent these kinds of abuses.

There are several strategies for rate limiting, such as:

  • Fixed Window. A fixed window allows a fixed number of requests in a timeframe—for example, 1000 requests per hour.
  • Sliding Log. This tracks all user requests in a log to check if a user exceeded the limit in any given window.
  • Token Bucket. This method adds tokens to a “bucket” at a set rate. Following a request a token is removed, if the bucket is empty, the request is denied.
  • Leaky Bucket. While similar to the token bucket, a leaky bucket starts to “leak,” or slow, requests instead of denying them when the bucket is empty. This way, it ensures a smooth output rate.

Different services require different limiting strategies, so you must understand your application’s needs and typical user behavior to choose the most appropriate one.

Encrypt data

Data encryption converts plain text data into a code or cipher text to prevent unauthorized access. Encryption ensures that sensitive data remains private by making it unreadable to anyone without the correct decryption key. It also provides a level of assurance that the data hasn’t been tampered with during transmission. If the encrypted data is altered in transit, it won’t decrypt correctly, which indicates to your users that there is a possible compromise.

Many industries have regulations requiring organizations to encrypt their data. For example, HIPAA  for the healthcare industry and PCI DSS for the financial sector both require encryption.

When it comes to encryption, keep these best practices in mind:

Encrypt data in transit and at rest. Data should be encrypted as it is sent across the network. Use SSL, HTTP, or TLS protocols to ensure encryption. You must also encrypt data while it’s stored – data at rest. That way, a malicious actor won’t be able to read data without an encryption key, even if they gain access to the storage system.

(Learn more about end-to-end and in-transit encryption.)

Manage keys securely. Your encryptions are only as secure as your keys. Keep them stored securely, rotate them regularly, and limit access to them for a healthy key management practice

Use up-to-date encryption algorithms. Encryption algorithms should be up-to-date and widely accepted as secure. For example, the Advanced Encryption Standard (AES), with a key size of 256 bits, is a widely-used and secure symmetric encryption algorithm.

Encryption is a critical component of a secure API and a significant part of a larger security strategy. 

Perform regular security testing

Regular security testing is essential to maintain your APIs' safety and integrity. It will help you find any vulnerabilities in your API and infrastructure to fix them before they’re exploited.

Some of the best types of security testing include:

Vulnerability scanning. Automated tools can scan your system for known vulnerabilities, such as out-of-date software or insecure configurations. This should be done regularly and after every major change in the system.

Penetration testing (Pen Testing). Simulated attacks on your system, conducted by external experts, will help uncover weaknesses in your security controls. The goal is to identify how far an attacker could get if they exploited identified vulnerabilities.

Static analysis. This method analyzes your application’s code without executing it to identify potential security vulnerabilities.

(Static analysis is key for application vulnerability management.)

Dynamic analysis. This tests the application while it operates, analyzing the code for vulnerabilities in the running environment.

Fuzzing. This type of testing involves sending unexpected or random data to the APIs to test their response and resilience to the inputs.

API-specific testing. This focuses on areas like checking for broken object-level authorization, testing user authentication and session management, validating input, and ensuring sensitive data is adequately encrypted.

Security testing is not a one-and-done activity but rather a continuous process that forms a crucial part of your API’s lifecycle.

(Testing can be time-consuming, thankfully autonomous testing can help.)

Safeguarding your API today 

APIs play an instrumental role in connecting services, enabling integration, and fostering innovation. However, this also comes with an increased risk of threats and attacks. You must implement robust API threat protection practices to: 

  • Ensure data protection
  • Maintain system integrity
  • Secure customer trust

A proactive approach to API security is critical in the modern digital landscape. Adopting best practices such as strong authentication and authorization systems, rate limiting, data encryption, and regular security testing effectively safeguards your API against potential threats. The quest for API security is an ongoing journey and demands vigilance, adaptations, and enhancement in line with evolving threat landscapes.

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Kayly Lange
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Kayly Lange

Kayly Lange is a freelance writer. As a tech and SaaS specialist, she enjoys helping companies achieve greater reach and success through informative articles. When she’s not writing, she enjoys being out in nature, cooking, and reading a wide range of novels. You can connect with Kayly on LinkedIn.