How API Penetration Testing Differs From Web Application Testing

Table of Contents

API penetration testing and web application testing are two very different types of comprehensive security testing. However, the majority of people view them as the same.

This blog post will discuss the critical differences between API penetration testing and web application testing. We will also provide a comprehensive guide for a practical API penetration test and web application testing meaning and types.

What is an API?

APIs are the connective tissue that runs between applications, enabling data movement from one application to another. All modern programming languages use some type or version of API, at least sometimes. The most common APIs are (SOAP) Simple Object Access Protocol and (REST) Representational State Transfer.

APIs are a crucial component in today’s application-based software. They enable companies to work with third-party partners, developers, and vendors, allowing data transfer across systems consisting of multiple applications or components performing together without having any integration problems between them all.

Since they use one common interface called an API which gives access to different types of tasks like calling functions on your device’s processor while being protected at every turn by computer safety measures, including firewalls designed specifically against malware attacks.

API penetration testing

Penetration testers are a crucial component of any company’s security strategy. They use the same techniques, tools, and tactics that real-world attackers would use to determine whether your APIs can withstand their attacks; this allows pentesters’ findings on confidential data within an enterprise before it happens.

API penetration test focuses and dynamics

The most comprehensive way to test for vulnerabilities in your API is through a penetration tester. A specialist will look at all aspects of how you implement and use these functions, from preparation through reporting, so any problems can be identified before they become significant issues.

At the end of a penetration test, you should receive detailed information about vulnerabilities found in your system. You can then discuss this with an independent third party who will guide you on how best to remediate them before their appearance becomes public knowledge or, worse yet, exploited by criminals.

Action plan of an API penetration test


You and the testing provider will agree on the scope of your test, which includes identifying goals for this particular test. You’ll go over the rules and guidelines for the test and confirm that there is enough time in the project timeline to complete it successfully without any delays or complications.


Gathering as much information about the target API is essential when preparing for testing. This includes authentication credentials and other details such as IP addresses or URLs that may be used in test cases.

Vulnerability analysis

Vulnerability analysis is the process of identifying vulnerabilities in an API, both application and network layers. To do this tester must log machine names along with sources on networks or applications services that are being used for accessing data from its target system(s).

Using automated tools combined with manual techniques will help them identify risks most likely leading up to possible attack surfaces. Their focus can then be directed accordingly based on these findings once prioritization has occurred.


Exploitation is where testers find vulnerabilities that may further discover genuine security gaps. This phase tests if these exploitable work as planned and documents findings for future reference so we can avoid repeating any mistakes made during this stage.


Now that testing is complete, it’s time to report the findings. This will involve providing a detailed explanation of all tested vulnerabilities with an option for clients who want more information or questions answered in person at their convenience after reviewing this report’s recommendations based on risk factor importance (this could include fixing high-risk bugs).

Reasons for API security testing

APIs have become a popular target for cybercriminals because they offer an easy way to steal data. A recent survey found that over 90% of organizations had at least one API security incident in 2020, and Gartner predicts there will be more attacks on this type of technology by 2022.

For example, Instagram allowed users to reset their passwords by sending a six-digit code. However, it did not limit the number of submissions per IP address. This led hackers to leverage this weakness, which TIME magazine reported as taking over multiple high-profile accounts during its incident coverage.

“The potential impact of a breach resulting from API vulnerabilities mandates the need for action.” This is an important point that should not be overlooked.

To protect against this risk, enterprises must first embed security by design into their process, building safe practices into every stage and stepping a long way in developing new APIs or updating existing ones through clever use “of static analysis.

API vulnerabilities

The Top 10 Vulnerabilities That Impact APIs is slightly adapted from the web application security guidance found in OWASP’s 2019 list of top ten software engineering challenges.

This document helps developers and testers mitigate unique risks associated with application programming interfaces by identifying common weaknesses rather than focusing on broad stroke vulnerabilities like last year’s version did, which applied to all kinds of applications, whether online-based systems (such as electronic commerce) or desktop applications.

The Top 10 Vulnerabilities That Impact APIs:

1- Injection flaws

An injection flaw is a type of security vulnerability that allows an attacker to insert malicious code into an application. This can allow the attacker to access sensitive data, modify data, or execute illegitimate actions on behalf of the user.

2- Cross-site scripting (XSS)

Cross-site scripting (XSS) is a type of security vulnerability that allows an attacker to inject malicious code into a web page. This can allow the attacker to steal sensitive information, such as cookies or session tokens, or hijack the user’s session entirely.

3- Broken authentication and session management

Broken authentication and session management is a type of security vulnerability that allows attackers to access a user’s account by exploiting weaknesses in the authentication and session management process. This can allow the attacker to impersonate the user, access sensitive data, or perform actions on behalf of the user.

4- Insufficient logging and monitoring

Insufficient logging and monitoring is a type of security vulnerability that allows an attacker to avoid detection by failing to log and monitor activity on the system properly. This can allow the attacker to gain access to sensitive data, modify data, or perform actions without being detected.

5- Insecure direct object references

Insecure direct object references are a type of security vulnerability that allows an attacker to directly access an object, such as a file or database record, using its references, such as its name or ID. This can allow the attacker to view or modify sensitive data.

6- Security misconfiguration

Security misconfiguration is a type of vulnerability that occurs when a system is improperly configured, leaving it open to attack. This can allow the attacker to gain access to sensitive data, modify data, or perform actions on the system.

7- Sensitive data discovery

Sensitive data discovery is a type of security vulnerability that allows attackers to find and view sensitive information, such as passwords, credit card numbers, or Social Security numbers. This can allow the attacker to access accounts or perform identity theft.

8- Cross-site request forgery (CSRF)

Cross-site request forgery (CSRF) is a type of security vulnerability that allows an attacker to inject malicious code into a web page that then executes an illegitimate action on behalf of the user. This can allow the attacker to access sensitive data, modify data, or perform actions on behalf of the user.

9- Using components with known vulnerabilities

Using components with known vulnerabilities is a type of security vulnerability that occurs when an application uses a third-party component with a known security flaw. This can allow the attacker to gain access to sensitive data, modify data, or perform actions on behalf of the user.

10- Insufficient supply chain security

Insufficient supply chain security is a type of security vulnerability that allows an attacker to compromise the software or hardware used by an organization. This can allow the attacker to gain access to sensitive data, modify data, or perform actions on behalf of the user.

Web applications testing

Automated web testing is a crucial step in the development process for any web-based application. A thorough review of your site’s UI design and functionality will ensure that live users can accept it before going live, giving you peace knowing no hidden surprises are waiting to pop up on launch day.

Web application testing tools

There are many tools to perform web applications testing; the best web testing tools are as follows:


BitBar will ensure you’re providing your customers with the best web and mobile experience on current browsers, including real devices. With their cloud-based testing lab for cross-platform browsing, it’s easy to run manual tests across desktop or tablet modes without having too much trouble.


Loadninja is a powerful tool that lets you test your web application with real browsers at scale, using scripts recorded in seconds and played back immediately after for instant analysis. This approach offers unparalleled insight into where performance problems lie without having to wait hours or days until the next scheduled recording.


LambdaTest’s cloud-based cross-browser testing platform offers a way to make sure your website/web app works seamlessly across desktop and mobile browsers.

Web application testing checklists

Functionality testing

The links in web pages, database connections, and forms used for submitting or getting information from the user should all be tested.

An example of a project is advertiser/affiliate sign-up steps, which are different but dependent upon each other. So they must execute correctly during both manual and automated tastings.

There are also field validations like email ids (to prevent fraud), financial info checking, etc.; these can happen manually or automatically, depending on what is more appropriate for the application.

Usability testing

Usability testing is a process by which the human-computer interaction characteristics of an interface are measured and weaknesses identified for correction.

Navigation means how users surf across web pages, different controls like buttons or boxes on each page, and links that take them to other parts within your site’s architecture.

It also involves understanding where these navigation points may be located within any given document, so they’re always accessible without having difficulty finding what you need when needed simply because there were no intuitively convenient places offered upfront.

This includes attention to font selection (or lack thereof), color schemes/themes, and overall presentation.

Interface testing

Web testers must ensure that all server-side interactions are correctly executed and that errors in databases or web interfaces don’t cause problems for end users.

These include verifying compatibility with software, hardware & network devices; checking if connections between these servers can be interrupted without affecting transaction outcomes.

The output should have more word choices such as “analogy” instead of just saying ‘like.’ It also needed organization by putting sentences together based on off-topic similarity rather than Transact SQL injection.

Compatibility testing

Browser compatibility has been the most influential part of website testing.

Some applications depend on their specific browsers and settings to function correctly, making it difficult for others who use different platforms or operating systems without any cross-supported standards across them all.

Leading to errors like crashing programs when trying to do something simple. You must ensure your codes can handle various types of devices, so no matter what kind someone uses, they’ll still be able to make sense of whatever content is displayed.

Performance testing

Stress testing is a way to see how your website handles overload or if it has limitations that can’t handle heavy load times. You should test for software errors such as memory leaks when you’re under pressure from large input data sets and simultaneous user requests on specific pages, among other things.

Security testing

Some might think that security starts with locks, but it’s more like layers. The first layer of protection is your browser settings; ensure you’re not loading anything outside of these secure boundaries when accessing sensitive websites or logins for the first time.

So they can’t be easily tricked or captured by an attacker who gains access through malware on their computer without permission (eavesdropping). If this doesn’t work, try changing the URL options directly.

api penetration testing

Types of web application testing

Website development has many types, about 20 in total. All these different websites have been classified into four main categories: static website banner ads (the most common), dynamic ad units that react to visitors’ actions or mouseovers on pages, social media integrated versions of your site where content can be shared via Facebook & Twitter, etc.

App-based interactions allow users access through mobile operating systems such as iTunes Store links so that they may download applications developed internally by Apple Incorporated.

How API penetration testing differs from web application testing

API penetration testing is a type of testing that seeks to identify vulnerabilities in an application programming interface (API). Unlike web application testing, which focuses on the user interface (UI) and transactions, API penetration testing drills down into the logic and functionality of the API itself.

To effectively test an API, penetration testers need a good understanding of its inner workings. They must know how data is passed back and forth between the client and server and how different inputs will affect the output. To this end, API penetration testing is more technical than web application testing.

One of the critical differences between API and web application tests is the scope of what’s being tested. A web application test focuses on the UI and the transactions between the user and the application.

On the other hand, an API test focuses on testing the logic and functionality of the API itself. This means testing how different inputs affect the output and what kind of data is passed back and forth between the client and server.

API tests are typically more technical than web application tests, as they require a good understanding of the API’s inner workings.

To effectively test an API, penetration testers need to know how data is passed back and forth between the client and server and how different inputs will affect the output.


So, what’s the difference? API penetration testing is similar to web application testing in that testers look for vulnerabilities that a malicious actor could exploit.

The main difference is that APIs are used to access and interact with backend systems, whereas web applications are front-end only. This makes APIs more attractive targets for hackers, as they can provide access to sensitive data and system resources.

That’s why it’s crucial to ensure your APIs are secure by performing regular penetration tests.

Contact our experts today if you want to know more about how we can help you protect your business-critical APIs and web apps.

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