Web penetration testing is an important tool that is used by security professionals to test the integrity of web-facing cyber assets and systems. Penetration testing for web services is necessary to highlight risk factors associated with key vulnerabilities in existing cybersecurity implementations. Despite the importance of web penetration testing, many people outside of the cybersecurity industry fail to recognize the importance of conducting regular penetration testing. In this article, we’ll outline what web penetration testing is, explore web application penetration testing methodology, and discuss why it is a necessary component of any comprehensive security assessment.
What is Web Penetration Testing?
Web penetration testing is used by cybersecurity professionals to assess the integrity of existing cybersecurity efforts. Penetration testing is used as part of a comprehensive security assessment for threat and vulnerability management. During a security assessment an organization’s cyber assets and systems are inventoried, studied, and scanned to expose any vulnerabilities. Once a vulnerability or vulnerabilities have been identified, they are then tested to see if they are exploitable by malicious actors through penetration testing. Penetration testing attempts to show if a vulnerability is real, and what the risk of exploitation for that vulnerability is.
Web penetration testing specifically targets applications with browser based clients. This encompasses the vast majority of applications used in today’s businesses. Because of the wide use of web-based applications, web penetration testing occupies a central location in any modern cybersecurity implementation. Web-facing applications can give malicious actors access to personally identifiable information (PII), protected health information, intellectual property (IP), as well as unwanted access to sensitive systems and assets. Because of this, the threat of an attack against a web-based client is particularly acute.
Unlike physical systems and assets, web-based applications have an increased level of exposure to outside attacks. Due to this, it is important to regularly assess a cybersecurity implementation to determine if vulnerabilities are exploitable. Web penetration testing can also be used as a means to test the effectiveness of an existing cybersecurity posture. How an organization deals with a successful penetration can highlight operational and organizational deficiencies that can be corrected before a real attack takes place.
Web Penetration Testing Fundamentals
At its core, web penetration testing involves a cybersecurity professional mounting an attack against a web-based application. This attack is conducted to attempt to gain access to systems that an attacker shouldn’t have access to. Once the penetration tester has gained access through a vulnerability, they then attempt to exploit that access to gain further penetration into the system. Put another way, a web penetration test involves a friendly actor mounting an attack against a system as if they were a malicious actor.
Web penetration testing can be done in a number of ways, and use a number of tools. In some cases, a cybersecurity professional may attempt to use hacking tools readily available to malicious actors on systems in a sandbox environment. In other cases, a cybersecurity professional may conduct penetration testing against live systems to assess real-world common vulnerabilities. The variety of ways in which a web penetration test can be conducted limits the ability to distill the process into a simple format. Rather than attempt to, we’ll break down the web application testing methodology.
Web penetration testing is generally conducted in one of three ways. These are known as black box, white box, and grey box tests. Each of these types of penetration tests has advantages and disadvantages, however all of them are attempting to accomplish the same goal.
A black box web penetration test occurs when the penetration tester has no prior knowledge of the target. Through the course of the penetration test, the tester must gather information about the target, assess systems and applications, find vulnerabilities, and attempt to exploit those vulnerabilities. The advantage of a black box test is that it closely replicates the course of a malicious attack. Through necessity, the tester will have to approach the target the same way as a malicious attacker, which can provide valuable insight. On the downside, a black box penetration test is time-consuming and labor intensive. By its very nature, a black box test is more general in scope than a white or grey box test.
A white box test is one where the penetration tester already has knowledge of the system, organization, and vulnerability that they are testing. White box penetration tests are much more common than black box, and are used to target specific vulnerabilities to assess the risks that they pose. White box tests lack the comprehensive reconnaissance required during a black box test, due to the fact that the tester already has ready access to information about the target of the test. White box tests are advantageous because they are focused, targeted penetration tests that can give a clear picture of an identified vulnerability.
A grey box test combines elements of both a white and black box test. In a grey box test, the penetration tester will typically have some information about the target, but won’t have the granular level of detail that you might see in a white box test. The client may provide a level of information that an attacker would generally be able to acquire as a starting point for the test.
The different types of web penetration tests are used to fulfil different functions by clients and security assessors. White box tests are comprehensive, and can be used to conduct penetration testing on the entirety of web applications used by a client. In contrast, black box tests are staged as if being conducted by a malicious actor, and can yield important insights about how an organization’s vulnerabilities and weaknesses are assessed and exploited from the outside.
Just as there are differences between the types of penetration tests, there are also differences in the testing methodology that security professionals use to test web systems. Because of this, it is impossible to define a definitive methodology that is used by everyone. Rather, a general outline of the web penetration testing methodology can be helpful to illustrate the steps involved in web penetration testing. There are, broadly, four phases to web penetration testing. These are reconnaissance, scanning, exploitation, and access maintenance.
The first phase in a web penetration test is generally the reconnaissance phase. During this period the tester will gather as much information about the target as possible. This includes information about their organization, systems, and operations. This information may yield insight into potential avenues of attack. In some web penetration testing scenarios the information gathering phase will be minimized or eliminated. This is often the case with white box penetration testing, which is often conducted with a full-field view of the target including all information relevant to the test itself. During a black box penetration test, the reconnaissance phase will be lengthy and time consuming, and may involve a variety of information gathering techniques including social engineering.
The second phase of a web penetration test involves scanning the target’s systems. During the first phase, testers may acquire or be provided with a list of systems to target and their respective IP addresses. Scanning involves assessing these cyber assets for vulnerabilities. This can be done through a variety of methods and using a number of different tools and approaches. The purpose of the scanning phase is to expose vulnerabilities that have the potential to give the tester access to protected systems or information. During a comprehensive security assessment, a vulnerability scan is conducted which would fulfill the same function.
During the exploitation phase of a web penetration test, the tester attempts to gain access to systems or data through the vulnerabilities identified during the scanning phase. During the web penetration testing exploitation phase, the tester may attempt to gain access to web-based applications or sensitive data by focusing on vulnerabilities on the servers themselves. Often, these vulnerabilities are present due to poor patch management or out-of-date systems, which give malicious actors easy access to sensitive systems. The exploitation phase cannot be distilled to one attack method or vector, particularly when discussing web-based attacks. Due to the proliferation of applications, systems, and devices connected to the internet, there are a wide range of techniques and tools that are used during the exploitation phase.
The final phase of a web-penetration test involves maintaining access once an exploit payload has been deployed. The penetration tester may try to see if they can maintain access to critical information or systems over time while evading detection. Penetration testers may not always simulate the extraction of data or obfuscation of the attack which are typical in a malicious attack. This phase may also involve the penetration tester attempting to escalate their privileges within the system, giving them further access to systems or data. The final phase of penetration testing can yield import insights into security responses, access control measures, and system resilience once an attacker has gained a foothold within your network.
As is clear from the above methodology, penetration testing for web services can closely track the attack pattern that a malicious actor will employ to gain access to protected data or systems. The phases of penetration testing mimic the process used by those unfamiliar with an organization or network. The above methodology is necessarily broad due to the fact that each penetration test may be carried out differently. This can depend on whether the text is a white, black, or grey box test, and whether the penetration tester has intimate knowledge of the target systems. Ultimately, the goal of a penetration test is to find a vulnerability in a system, exploit that vulnerability, and be able to prove that the exploit is repeatable. In doing so, penetration testing serves as an important benchmark for how at-risk a web-based application or system is to outside attack.
Why Bother With Web Penetration Testing?
Some organizations may wonder whether web penetration testing is worthwhile. The reality is that the scope of risk facing organizations today is vastly wider than at any previous time. This is particularly true of internet connected applications and devices. Not only must devices and applications be hardened against outside attack, but how those applications and devices communicate with each other on internal networks must also be understood and protected. The proliferation of personal devices being used to conduct day-to-day business further increases the risk factor for today’s organizations.
A web penetration testing service is an integral tool that organizations can use to ensure their cybersecurity implementation is effective. Web penetration testing is the means through which a security assessor can determine if web application vulnerabilities highlighted during a security scan are real. If a vulnerability is exploitable in the real world, a penetration test will help determine the risk associated with the vulnerability. Web penetration testing is often complex and time consuming, yet remains necessary to understand the effectiveness of your current cybersecurity posture.
While the importance of web penetration testing cannot be understated, it is also vital to keep in mind that penetration testing functions by checking your current cybersecurity efforts. If your cybersecurity is lax, penetration testing does little except tell you what you already know. In order to be truly effective, penetration testing must be used in conjunction with other tools that cybersecurity professionals use to comprehensively test every facet of your organization’s cybersecurity. If you aren’t sure if your cybersecurity is adequate for the threats facing your organization, consider using a third-party security assessor such as the RSI Security experts to perform a comprehensive security assessment for your cybersecurity solutions. By using outside experts to assess your cybersecurity efforts and posture, you will be able to identify and fix security vulnerabilities, security risks, or flaws before a malicious actor stages an attack. Additionally, the ongoing data protection that third-party security assessors offer helps organizations maintain the type of proactive cybersecurity posture that is necessary in today’s world to guard against advanced persistent threats. Request a consultation for threat and vulnerability management today.
 Joseph Muniz and Aamir Lakhani, Web Penetration Testing with Kali Linux?: A Practical Guide to Implementing Penetration Testing Strategies on Websites, Web Applications, and Standard Web Protocols with Kali Linux (Birmingham: Packt Publishing, 2013), 7-8.
 Ric Messier, “What Is Penetration Testing?,” in Penetration Testing Basics: A Quick-Start Guide to Breaking into Systems, ed. Ric Messier (Berkeley, CA: Apress, 2016), 5-7, https://doi.org/10.1007/978-1-4842-1857-0_1.
 Pat Engebretson, The Basics of Hacking and Penetration Testing?: Ethical Hacking and Penetration Testing Made Easy, vol. 2nd ed (Amsterdam: Syngress, 2013), 14-17.