The Critical Need for API Security Testing

Application security penetration tests once were a novelty, a luxury that only organizations with security budget to burn would indulge in. But as more and more resources have moved to the web, including mission-critical enterprise applications, these exercises have become a vital part of most security programs.

More recently, many enterprises have expanded their application security strategy to also include API security tests, in an effort to ensure that attackers can’t gain access to any exposed API endpoint. APIs may not be the most obvious intrusion point for attackers, but they can be vulnerable to a host of issues and, if left exposed, make easy pickings for opportunistic bad actors.

What is an API?

Application programming interfaces (APIs) are software interfaces that enable applications and services to interact and communicate with each other. A web application may have several separate API endpoints, which are the specific entry points that the API code talks to, and those endpoints are frequent targets for attackers looking to gain a foothold in a specific web app. Because so much enterprise and consumer computing has moved online, API attacks are very common and can be quite profitable for bad actors. 

Why API Security Differs from Traditional AppSec

Traditional application security testing focuses on user-facing vulnerabilities, typically testing the entire application as a whole. APIs, however, expose backend logic and critical data pathways, making them unique in several ways:

• Specific Attack Vectors: APIs are particularly susceptible to vulnerabilities like Broken Object Level Authorization (BOLA), excessive data exposure, and mass assignment attacks, which are less common in traditional AppSec testing. GraphQL, which is widely used in APIs, is also subject to common attack vectors such as command injection and DoS.
• Exposing Backend Logic: APIs often reveal backend structures such as database queries or sensitive internal processes, providing attackers with additional pathways to exploit vulnerabilities.

This backend exposure and the nature of APIs in connecting modern applications make API security a unique challenge that requires specialized testing approaches.

Benefits of API Security Tests

For modern enterprises, protecting sensitive data is among the top priorities, regardless of the industry they operate in, and they set aside significant amounts of money and resources for security programs and personnel. But there are innumerable ways for attackers to gain access to valuable data, and attacking vulnerable APIs is an underrated method to accomplish that goal.

A new study by Akamai found that 84% of respondents had experienced an API-related security incident in the past year, a number that rose from 78% in 2023. API security testing is designed to identify weaknesses in those APIs and fix them before attackers can take advantage of them and steal valuable data. These tests also can find issues that can be exploited to limit or deny access to resources, which can cause customer frustration. 

The Mechanics of an API Pen Test

Traditional application security tests take a broad approach, testing a variety of aspects of the target application to look for potential vulnerabilities and exploitation paths. Most organizations hire outside firms to perform these tests and will typically do them on an annual basis, or even more often if required by regulations.

Those tests generally come in two flavors: dynamic application security tests (DAST) and static application security tests (SAST). DAST tools are designed to look at apps as they run and discover potentially exploitable vulnerabilities, while SAST tools look at the static source code of an app. The approaches are different, but the goal is the same: discovering vulnerabilities. 

API penetration tests take a different tack. Rather than running DAST or SAST tools against the target application, these tests use specialized tests to do several different findings. In general, API penetration tests are tightly focused on how applications ingest and handle data in the backend rather than on the user-facing aspects of the application. 

• Tools and Techniques: API testing often involves tools like Postman, Burp Suite, and OWASP ZAP to simulate requests and identify vulnerabilities.
• Scoping and Endpoint Discovery: Comprehensive scoping, including documentation reviews and identifying "shadow APIs," is critical to ensure all endpoints are tested.
  
  

The main goals of an API penetration test include:

• Looking for common API-related vulnerabilities such as SQL injection, command injection, server-side request forgery, and others. 
• Identifying all of the application’s API endpoints, including non-obvious ones that could present weaknesses
• Inspecting the authorization model of the API to identify broken object-level authorization checks, improper authorization, and function-level authorization issues. 
• Identifying authentication problems that could allow an attacker to compromise authentication tokens and gain control of a user’s account
• Identifying input-sanitization problems, specifically with user-supplied input. 
• Session-management problems that can cause authorization weaknesses

Without comprehensive testing, vulnerable APIs can remain exposed indefinitely, inviting attackers to target them. But like other security tests and programs, API testing needs to be scoped and planned properly in order to ensure that the test is effective and successful.

Secure Your APIs with Expert Testing

API security testing is not just a checkbox exercise; it’s an essential component of any robust security program. With APIs forming the backbone of modern applications, ensuring their security requires expertise, proper scoping, and a combination of automated tools and manual testing.

Secure Ideas specializes in API penetration testing and can help your organization uncover hidden vulnerabilities, protect critical data, and build customer trust. Contact us today to learn more about our API security testing services and how we can help safeguard your applications.