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What Is Web Application Penetration Testing

September 29, 2023

Web Application Penetration Testing: The Ultimate Guide

This comprehensive guide on web application penetration testing covers everything you need to know about the importance, methodologies, and tools for a successful penetration test.

Alex Drozdov

Software Implementation Consultant

Nowadays, when the world is rapidly growing into digitalization, web apps have become a vital part of our lives. From e-commerce platforms to social networking sites and online banking, these apps handle sensitive user data and transactions. Consequently, the need for robust security grows in tandem with the number of users. This is when web application penetration testing comes into play. Our article is a quick, all-around look at the world of web application pentest, including its importance, methods, techniques, and tools.

What Is Web Application Penetration Testing?

Penetration testing, often known as pentest or ethical hacking, is the process of evaluating a software's security against simulated attacks by expert testers before real-world hackers do it. The main goal is to find any vulnerabilities in the system and then suggest a remediation plan. 

The Importance of Web Application Penetration Testing

Penetration testing is an integral part of any robust security program and is normally carried out by individuals or a company with expertise in the sector. First off, pentest allows for uncovering any vulnerabilities in the software that may have gone unreported during development or routine audits. Second, it reduces the likelihood of data breaches, unauthorized access, and other security problems by identifying and fixing flaws in a system before they can be exploited by hackers. Finally, conducting regular penetration testing demonstrates a dedication to consumers' privacy and security, which will surely boost trust and loyalty.

Penetration Testing

Types of Tools and Techniques

When performing a pentest, professionals incorporate a variety of tools and methods as part of their process. Here are some of the primary ones:

Manual Testing

As mentioned earlier, penetration testing is most often carried out manually. Experts manually identify vulnerabilities that automated tools may have missed. They thoroughly analyze the source code and functionality of the app as well as gain insight into the design and logic of the application.

Automated Testing

On the other hand, automated pentest is always conducted by specialized tools that scan applications for security flaws that have previously been discovered and patched. While automated tools can greatly speed up the testing process, they have the potential to cause false positives and false negatives. Thus, they may not detect all types of vulnerabilities. Yet, its efficiency is undeniable, especially for repetitive tasks.

Static Analysis Tools

Without actually running the code, static analysis tools investigate the web application's source code to locate vulnerabilities. This tool makes it possible to uncover vulnerabilities such as insecure coding techniques, hard-coded credentials, and various other issues.

Dynamic Analysis Tools

While static analysis tools examine software before it runs, dynamic analysis tools interact with an application as it runs, looking for security flaws as they become evident. This technique helps find problems such as input validation flaws and injection attacks.


Lastly, there is fuzzing, during which testers intentionally crash or otherwise make a web app behave unexpectedly by injecting a large amount of random data into it. It simplifies the search for flaws in database handling and input validation procedures.

Methodologies of Web Application Penetration Testing

In practice, web application penetration testing not only involves the use of tools but also integrates a range of methods within its process, creating a structured framework. Some of the primary techniques include:

Penetration Testing Methodologies

OWASP Testing Guide

First comes the Open Web Application Security Project or OWASP Testing Guide which is quite a common methodology that employs a wide variety of testing from White Box testing to 

XML testing. These approaches are routinely updated to reflect changes in the threat landscape and provide clear instructions for testing web apps for security flaws.

Pros: Variety of testing approaches, clear instructions

Cons: Potentially outdated information, limited focus on process flaws

Open Source Security Testing Methodology Manual (OSSTMM)

The Open Source Security Testing Methodology Manual (OSSTMM) is yet another all-encompassing framework. Its main focus is security testing from a holistic perspective. While it does not delve deeply into the technical difficulties, it does discuss the importance of addressing the human factor, process flaws, and other forms of physical security.

Pros: Holistic approach, adaptability, threat-centric

Cons: Complex, resource-intensive, limited technical depth

Penetration Testing Execution Standard (PTES)

The Penetration Testing Execution Standard (PTES) is a framework that integrates pre-engagement contacts, threat modeling, vulnerability analysis, and reporting into the whole scope of penetration testing. It emphasizes a thorough and methodical approach to testing.

Pros: comprehensive structure, thorough methodology, flexibility

Cons: overlapping phases, learning curve

Phases of web application penetration testing

Now that we've discussed what a web apps pentest is and why it's vital, let's go deeper into the process and get acquainted with the phases it consists of. We cannot give an exact number of stages but most often web application penetration testing consists of these 5 main stages we’re going to discuss below. 

Penetration Testing Steps


In the first phase, known as "reconnaissance," testers collect data on the domains, IP addresses, and technologies that will be used in the targeted application. This information equips them with a thorough comprehension of the vulnerability vectors within the program.

Mapping and Discovery

Next comes mapping and discovery, during which testers dig deeper to locate any possible entry points and security flaws in the software. During this stage, testers employ such techniques as crawling, spidering, and mapping the application's structure.

Vulnerability Analysis

One of the vital stages of pentest is vulnerability analysis. During this phase, testers actively attempt to take advantage of any vulnerabilities they have found to determine how serious they are. This is useful for grasping the actual dangers posed by each vulnerability.


We pass to the exploitation phase during which testers try to attempt and gain unauthorized access or control over the application using the identified vulnerabilities. Thus, when accessing the flaws, they validate the severity of the vulnerabilities and potential impact.


Finally, reporting! In this phase, testers compile a report detailing the vulnerabilities they found, how they'll affect your system, and what you can do about it. This report will later come in handy for developing a secure system and identifying possible vulnerabilities in advance. 

Techniques Used in Web Application Penetration Testing

Moving forward into the topic, let’s discuss what techniques are generally used by testers and what their impact is!

Penetration Testing Techniques

Injection attacks

During injection attacks, testers will pretend to be hackers and insert malicious code into your app's inputs (such as forms or URLs). Experts do so to see if your software behaves oddly or gives out private information when it gets baffled.  

Cross-site scripting (XSS) attacks

In cross-site scripting (XSS) attacks, hackers try to manipulate users' browsers into doing malicious actions by inserting dangerous scripts into your app. They are like web secret agents who check to see if your app can find and stop these tricks before they do any damage.

Cross-site request forgery (CSRF) attacks

As part of a penetration test, a CSRF attack will attempt to trick your application into performing tasks for which it does not have permission. Attackers may use deceptive methods, such as sending seemingly harmless emails or leading to websites that contain destructive orders. If you give in, your app could leak private data without your permission. 

Broken authentication and session management

To gain unauthorized access to your app, testers may employ broken authentication and session management techniques. They're like virtual robbers, checking to see if your app can spot them.

Insecure cryptographic storage

Lastly, insecure encryption occurs when a "known" hacker thoroughly examines the inner workings of your app's cryptographic safeguards to determine their efficacy. Thus, they assist in revealing any vulnerabilities in your app's encryption, assessing the encryption method, and granting you a plan of remediation. 

Types of Web Application Penetration Testing Tools

Burp Suite

  • Comprehensive Web Vulnerability Scanner: Burp Suite carefully checks your app for vulnerabilities covering a wide range of possible means of attack. 

  • Mapping and Analysis: It clearly shows how your app is built and how it works, giving you a clear picture of possible entry spots.

  • Exploitation Capabilities: Using Burp Suite, you can simulate attacks on your app and see how it reacts to potential threats.

  • Detailed Reporting: Finally, it produces in-depth reports that describe the security vulnerabilities it has found and offers advice on how to fix them.


  • Automated and Manual Scanning: OWASP ZAP  supports both automated scanning and manual testing, accommodating different testing methodologies.

  • Security Detection: OWASP ZAP is set up to find security flaws like injection attacks, CSRF, XSS, and more.

  • Reporting: It provides detailed reports about the vulnerabilities and possible risks that have been found.

  • Flexible Configuration: Users can personalize scans and tests based on their app's specific needs.


  • Automated Scanning: Acunetix simplifies the scanning process, making it easy to detect any security flaws.

  • Deep Analysis and Integration Capabilities: It performs in-depth analysis of web applications, and APIs, as well as integrates with issue-tracking tools.

  • Advanced Crawler: It swiftly explores intricate web programs, guaranteeing thorough inspection.

  • Reporting: Acunetix provides detailed vulnerability reports with prioritized recommendations.


  • Scan Automation: Netsparker simplifies finding security flaws by eliminating the need for manual inspection.

  • Complex Vulnerabilities: It is adept at finding security flaws that are difficult for more basic scanners to detect.

  • Proof-based scanning: Netsparker employs proof-based scanning in which vulnerabilities are validated after being discovered by exploiting them.

  • Accurate Reporting: It creates comprehensive reports with useful insights and suggestions for corrective measures.


  • Exploit Development: Metasploit is useful for creating and testing exploits for security flaws.

  • Vulnerability Simulation: Vulnerability simulation allows you to test how well your app handles simulated attacks.

  • Post-Exploitation: Metasploit helps testers understand potential post-attack scenarios, aiding in defense preparation.

  • Payloads and Modules: The tool offers a library of pre-built payloads and modules for various scenarios.

Web Application Penetration Testing Cost

The cost of a web application penetration testing service can vary significantly based on factors such as the complexity of the application, the size of the organization, and the chosen testing methodology.

Here’s a simplified price breakdown for performing penetration testing for a web application. Remember that these numbers might fluctuate greatly depending on the specifications of your application, the difficulty of the testing, and the service provider you select.

White box penetration testing$500 – $2000 per scan
Black box penetration testing$10,000 to $50,000 per scan
Grey box penetration testing$500 to $50,000 per scan

Why choose Yellow for Web Application Penetration Testing?

Simply put, with years of experience behind our team has the skills and experience to dig deep into your app and find any weak spots. For maximum safety, we employ cutting-edge techniques and the latest technologies to secure your app. Moreover, we don't just point out problems – we give you a clear plan to fix them. 

When teaming up with us, you're showing your users that their info is in safe hands. We back up our claims with a solid performance in the field of cybersecurity.

To sum up…

As a conclusion, securing web apps is a must in today's digital world. By using smart methods and tools, organizations can find and fix vulnerabilities early on. Penetration testing, from start to finish, gives valuable insights by uncovering potential weak spots like injection attacks and XSS vulnerabilities.

Investing in this testing is like a long-term safety plan. Sure, there's a cost, but it's way better than the trouble of cyberattacks – think money loss, legal issues, and damage to your reputation.

🚀 What is web application security?

Web application security is a set of processes, technologies, and methods that enable web servers, apps, and web services like APIs to avoid attacks and threats.

🚀 What are the different types of web application vulnerabilities?

There are dozens of web application vulnerabilities that may affect your software, yet the main ones include injection attacks, broken access control, data leaks, security misconfigurations, and insecure design.

🚀 How can I ensure that my web application is secure?

The best way to ensure your web application is secure is to conduct penetration testing and vulnerability scanning from time to time. Make sure to work with competent engineers that are crafted to make secure and up-to-date software.

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