What is Web Application Penetration Testing?

By Fortra's Digital Defense

These days, it seems like most businesses are dealing with a cybersecurity attack that leaks sensitive information to the public and wreaks havoc on their day-to-day operations. Vulnerability scans are a way to identify areas of weakness within an online security network, but they are not enough. Scanning for web application vulnerabilities in conjunction with penetration testing is a more efficient way to identify potential weakness and show a business the real-world consequences of an unauthorized user exploiting its flaws.


What is Web Application Penetration Testing?

During web application penetration testing, a security team will evaluate a network’s security by attempting to infiltrate it the way attackers would breach a company’s system. The security expert will examine the attack surface of all the company’s browser-based applications and use similar steps an unauthorized user would employ to gain access to the system’s valuable information.

The penetration test also ensures that developers create web applications that are not vulnerable to intruders. Anyone who develops web apps must be aware of all security threats before selling their product to a customer. Otherwise, they will jeopardize their reputation; most web application creators cannot quickly bounce back after data breaches.

Hiring a web application pen tester is an efficient way to ensure the app meets or exceeds its functionality, performance, security, and reliability standards.


What is the Purpose of Penetration Testing?

Assuming your company’s security system is secure against attacks is a common mistake. Technology is always evolving and improving, and cyber defense measures that worked yesterday may not work tomorrow. More people are developing internet resources and software that hackers can use to infiltrate a once-secure network system.

Web applications often store sensitive information that people can exploit for personal gain. Web app penetration testing identifies the ever-growing list of network vulnerabilities so that businesses can take the appropriate steps to patch any flaws and prevent threats to their information. Without a routine penetration test, a business’s data can find its way online, putting the organization and its clients at risk.

Every business uses at least one web application to conduct day-to-day tasks, whether it involves transferring money between various accounts, making purchases, or using open-source components to build a company web app.


What are Web Application Risks?

Web application penetration testers have a vast knowledge of app development and understand some of the mistakes developers make that allow online thieves to invade their application.

Here are some of the most common web application risks:

  • Cross-Site Scripting: Also known as XSS, this risk occurs with apps that execute scripts in a browser and respond to untrustworthy requests. Cyber attackers will use cross-site scripting to hijack a website, deface it, alter its cookie settings, or redirect unsuspecting users to websites where they can be tricked into divulging sensitive data.
  • Security Misconfiguration: This issue occurs when web app developers don’t correctly define the app’s security configurations and related components. Such vulnerabilities make it possible for hackers to gain unauthorized access to input fields and URLs.
  • SQL Injection: An SQL injection is a type of hacking whereby an unauthorized user changes the SQL statements on an app’s backend and tricks it into performing commands that give the hacker unauthorized access to information.
  • Vulnerable Components: The entire application must be secure, down to each component. Unfortunately, developers sometimes use old, unsupported features that are vulnerable to attacks. Unauthorized users will manipulate these weaknesses to access sensitive data or take control of the company’s network.
  • Broken Access Controls: Authorized network users can unintentionally gain access to system segments that extend beyond the reach of their designated duties, leaving the network susceptible to unauthorized use.


What are the Types of Penetration Testing?

Internal Penetration Testing

The internal pen test takes place within the organization over the LAN to test web applications on the company’s intranet. This process examines the system for vulnerabilities inside the firewall that an intruder could manipulate from the inside.

Unfortunately, many people assume cyberattacks occur from outside the network, not the other way around, but this is not wholly correct. Internal web application pen testing can uncover several potential issues that would not otherwise be identified, including:

  • Malicious attacks from disgruntled workers and contractors who no longer work for the company but are aware of passwords and security policies
  • Phishing attacks
  • Attacks by abusing user privileges or misusing unlocked workstations
  • Social engineering attacks to gain data by manipulating people

An internal web application penetration tester will conduct the test without the necessary network credentials in their attempt to find security vulnerabilities.

External Penetration Testing

Like the internal web app pen test, the external web application penetration test attempts to uncover security flaws but from outside the company’s network instead of inside. The security testing process also includes applications on the internet. During this process, the testers will simulate a hack as someone who wants to gain access to the system without knowledge of its infrastructure.

At the beginning of the test, the pen tester will use the company’s IP address without any other data. They will use public web pages on the internet for information gathering. If they find details about the target website, they will then use the data to compromise it.

This type of test includes IDS, servers, and firewalls.


What is the Web Penetration Testing Methodology?

There is a distinction between mobile applications and web applications. Penetration tests focus on the environment around a web app by gathering information about the app using public web pages. The end user will then use the details they glean to map out the network hosting the web application before investigating potential tampering and injection attacks.

How to Perform Penetration Testing for a Website

Cybersecurity experts will check for web application security vulnerabilities in three stages:

  • Information gathering (planning)
  • Execution (exploiting)
  • End planning (post-execution cleanup)

Information Gathering

Before testing can begin, the tester must determine which tests they will conduct, how to perform each test, and whether they need more information for all tasks. During this phase, the tester will collect as much data about the web application as possible, usually using open-source tools. Details include the app’s server type, links pages, programming languages, and database type.

There are two commonly used ways to collect data:

  • Active Reconnaissance: This method of information gathering requires the penetration tester to acquire data directly from the target system. An example of active reconnaissance is a DNS zone transfer, which uses the “nslookup” command to find the DNS server and “dig” to engage the DNS zone transfer. Another example is the DNS forward and a reverse lookup, which uses tools like Burp Suite to connect discovered domains with their respective IP addresses.
  • Passive Reconnaissance: The process of gathering data without explicitly engaging the target system is known as passive reconnaissance. To accomplish this task, the tester will collect data via the internet from broad-range sources like Google.

While gathering information for pen testing, the security expert will document all intel they have uncovered. Documentation will provide them with a baseline of data they can use to find and exploit vulnerabilities.


The web app pen testing professional will use the details they collect to initiate an attack simulation and exploit vulnerabilities. Testers can execute this part of the testing phase through manual testing or automated tool testing. While automated testing will reduce human error and produce quick results, manual testing is necessary for finding weaknesses that can yield false positives.

To accomplish this task, they will likely use several testing tools:

  • One of the primary testing tools, tests the framework, not just an application. Testers use it to choose and configure targeted exploits, payloads, and encoding schemas.
  • An all-in-one platform for web application vulnerability testing that is part of Kali Linux, a Debian-based Linux operating system for penetration testing.
  • Network scanner for finding vulnerabilities, malware, and misconfigurations. The goal is not to manipulate a security weakness but to give security experts who are testing systems and applications greater insight into a network’s problem areas, which they can later exploit using more appropriate tools.

End Planning

Once the penetration testing professional completes the project, they will report their findings to the business’s IT team. The company’s security experts and a member of quality assurance will review the report and consider remediation. Knowing about security flaws is not enough to maintain a sufficient security posture; they must fix the vulnerabilities uncovered by security testing.

Once remediation efforts are complete, the security team will need to conduct another round of penetration testing to ensure the application no longer has vulnerabilities. After the final test, the pen testing professional will revert the proxy settings back to their original positions, as they typically alter the proxy settings during testing.


Vulnerability Scans vs. Web Application Penetration Testing

Businesses often confuse penetration testing with vulnerability scanning. Though these functions can work in tandem with each other, they represent two separate control methods. Both must be understood to ensure a web application can stand up to threat actors.

The purpose of vulnerability scans is to detect weaknesses within network-connected devices like servers, routers, firewalls, and applications. Scanning will also identify the location of the flaws. The process offers a measure of application risk assessment without providing details about how a real-world exploit of the vulnerabilities will affect the business.

Web penetration testing is a more targeted approach to understanding holes in an application. Pen testing relies on a cybersecurity professional with advanced knowledge to simulate a cyberattack or mimic the mistakes someone may make that could potentially expose a business’s digital assets. Testers look for the most at-risk entry points to exploit.



Some companies hesitate to invest in penetration testing because leaders assume the testing process will be too expensive or time-consuming. Not testing the application or using less costly measures is no way to effectively find and address security weaknesses. The cost of doing nothing will be far greater than time and finances one would spend on a business’s web application security.

Don’t allow hackers to invade your web apps. The security experts at Digital Defense have over 20 years of experience providing businesses of all sizes with superior application security solutions to end users and MSPs, including web application penetration testing and vulnerability scanning.

About Digital Defense

Our SaaS platform supports Fortra Vulnerability Management, Web Application Scanning, and Active Threat Sweep that together provide:

  • Asset discovery and tracking
  • OS and web application risk assessment
  • Targeted malware threat assessment
  • Machine learning features that leverage threat intelligence
  • Agentless & agent-based scanning
  • Penetration testing for networks, mobile applications, and web applications
  • Compliance management. One of the world’s longest tenured PCI-Approved Scanning Vendors

Our SaaS platform virtually eliminates false-positives associated with legacy vulnerability management solutions, while also automating the tracking of dynamic and transient assets and prioritizing results based on business criticality.

About the Author

Mieng Lim, Vice President, Product Management has served as a security expert for Digital Defense, Inc. since 2001. Mieng takes a consultative approach to security having held prior roles in Operations, Quality Assurance and Sales Engineering. Mieng seamlessly blends technical expertise with real world scenarios to provide an entertaining and educational cyber security perspective. Mieng serves a mentor and STEM advocate encouraging young women to pursue careers in security and technology and volunteers with BSides San Antonio as a staff member. Mieng holds a Bachelor’s Degree in Computer Science with Minor in Sociology from Trinity University. 

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