Web Application Penetration Testing Fundamentals

As the complexity of cyber threats continues to increase, businesses are investing more resources than ever before to safeguard their systems from potential reputational and financial losses. One of the most popular approaches to security testing is web application penetration testing, often referred to as Pen Test or Pen Testing. This technique involves simulating malicious attacks on digital applications and networks to uncover vulnerabilities that could be exploited by cybercriminals.

Web application penetration testing is an essential security measure that involves simulating malicious attacks against application systems, such as APIs, front-end servers, and back-end servers. The purpose of this is to identify exploitable flaws that can be used to gain access to sensitive data. By conducting web application penetration tests, organisations are able to verify the security of their systems, identify any weaknesses, and gauge the potential damage that could be caused by an attack. In addition, businesses can then develop appropriate plans to mitigate any risks that have been identified.

Web application penetration testing types

For online applications, there are two primary methods of penetration testing:

  • Internal penetration testing

This type of testing is focused on web applications located within an organisation’s intranet. Its purpose is to identify any potential vulnerabilities that may exist behind the corporate firewall by attempting to gain access to the system using invalid credentials and by assessing the potential damage and avenues of attack. Common internal attack types include, but are not limited to, brute force attacks, privilege escalation, SQL injection, buffer overflow, and cross-site scripting.

  1. Phishing attack simulation
  2. Attacks by malicious employees
  3. Attacks using user privileges
  4. Attacks against social engineering
  • External penetration testing

Penetration testing, also known as ethical hacking, involves simulating external attacks against web applications hosted online. This type of testing involves evaluating the effectiveness of the target system’s firewalls, intrusion detection systems (IDS), Domain Name System (DNS), and front-end and back-end servers against potential external threats. The aim of this type of testing is to identify any weaknesses in the system and provide recommendations for improvement.

Aside from these, there are a few more techniques for pentesting, such as blind testing, double-blind testing, and targeted testing.

Web Application Penetration Testing Procedures

  • Reconnaissance and planning

This stage of the test process involves defining the goals and objectives, gathering the necessary information related to the target system (such as servers, networks, domain names, etc.), and selecting the testing tools and procedures. Reconnaissance can be conducted in two ways depending on the level of contact needed with the target system.

  • Active Reconnaissance
    During active reconnaissance, the tester employs a variety of techniques with the aim of obtaining information about the target system. These techniques involve the tester proactively gathering information from the target system, as opposed to passively observing data. Examples of active reconnaissance techniques include:
    • Shodan is a network scanner.
    • Web application fingerprinting
    • DNS zone migration
    • DNS lookups, both forward and reverse
  • Passive Reconnaissance
    As a web application penetration tester, it is important to gather information from the internet without the need to directly interact with the target system. To make this task easier, there are a number of tools available. Some of the most commonly used tools for web application penetration testing include:
    • W3af
    • Veracode
    • Burp Suite
    • SQLMap
    • ZAP
    • Metasploit
    • Acunetix
    • Vega
    • Skipfish
    • Ratproxy
    • NetSparker
    • Watcher
  • Exploitation and scanning

    Once testers have acquired all the necessary data, they can begin to simulate cyber-attacks on web applications to identify their weaknesses. Following this, they may exploit such vulnerabilities by obtaining privileged access, collecting data, altering system settings, capturing traffic, and engaging in other activities to evaluate the amount of damage that may be inflicted on the target system. The following are some possible test scenarios for performing these simulated cyber-attacks:
    • Site-to-Site Scripting
    • Misconfigurations in Security
    • Injection of SQL
    • Cracking Passwords
    • Attacks on Caching Servers
    • Forgery of Cross-Site Requests
    • faults in file upload
    • Authentication and session management issues
  • Reporting and analysis

This report has been created to provide an in-depth summary of the key results of the testing procedure. It contains all pertinent information, including any sensitive data that was exposed, a listing of any vulnerabilities that were exploited, the duration of time the tester was able to remain undetected within the system, and more. This data is then shared with security experts, who utilise it to evaluate and adjust the organisation’s Web Application Firewall (WAF) configurations, repair the essential components, and establish application security protocols to patch any potential vulnerabilities and protect against future assaults.


Web applications are the backbone of revenue generation for many businesses, with hundreds of transactions occurring every second. It is imperative for businesses to ensure the security of these applications against potential threats and data theft. Web application penetration testing is a great way for companies to maximise system security and to prepare for any future risks. Security professionals use the latest testing tools to uncover vulnerabilities, minimise potential risks and update security policies. These tests can include reviewing the source code, servers, web application firewalls (WAF), database connections, application programming interfaces (APIs), and third-party integrations.

Highly-skilled software engineers are essential for the successful development of a top-notch web application. It is equally important to ensure the security of the application is up-to-date and reliable. If you are looking to expand your software engineering department, we suggest you give Works a try. We are confident that you will be delighted with the results.

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