Web Application Penetration Testing: A Comprehensive Guide

What is Web Application Penetration Testing?

A web application penetration test, or pentest, is a type of cybersecurity assessment carried out by a penetration tester, or ethical hacker, in an attempt to identify vulnerabilities and offer remediation advice for an business’s web app. 

Depending on the type of web app pentest carried out, something that we will address shortly, this cybersecurity assessment will attempt to mimic a real-life attack so as to provide valuable feedback on how well the web app security would fare against a genuine attack. 

Once the test has been carried out, the pentester will grade the severity of the vulnerabilities they found to help the development team with vulnerability prioritisation.

If you want to learn more about penetration testing in general, check out our comprehensive guide. 

Why are Web Application Penetration Tests Important?

Cybersecurity is an essential part of web app development thanks to the enormous amount of employee, customer or partner data a web app can store. 

By carrying out regular web app penetration tests, you can identify and patch vulnerabilities quickly and efficiently before they can be exploited by cybercriminals.

Taking a proactive approach to web app security will always pay dividends as you ensure compliance with industry standards like such as GDPR, PCI DSS, and ISO 27001, whilst safeguarding your assets and reputation.

Types of Web Application Penetration Test

Much like other penetration tests out there, i.e., network penetration testing, there’s no single type of web application penetration test. Most of the time, the type of test performed depends entirely on the needs of the business, the scope of the test, and the resources available. 

That being said, here are a few examples of types of web app pentest:

Black Box Testing

In black box penetration testing, sometimes referred to as blind testing, the pentester has no prior knowledge of the application. This perfectly simulates a real-life attack because, unless the attacker is an insider, it’s unlikely that they will know anything about the web app until they start attacking.

White Box Testing

The complete opposite to black box testing, and sometimes referred to as open testing, in a white box penetration test, the pentester has full access to the application’s source code, enabling a thorough assessment of its security mechanisms.

Grey Box Testing

The middle ground between black and white box pentesting, in grey box or transluscent testing, the tester has limited knowledge of the application such as login credentials, simulating an insider or targeted attack.

Phases of Web Application Penetration Testing

Similar to the different types of web app test, there’s no one-size-fits-all way of carrying out a security assessment like this. The best we can do is to highlight some of the common phases.

Planning and Reconaissance

In this phase, the scope of the test is defined, and information about the target application is collected. This includes understanding the application’s architecture, user roles, and potential entry points.

Scanning and Vulnerability Detection

Automated tools are used to scan the application for known vulnerabilities, such as outdated software, misconfigurations, or weak encryption. 

There is a fair bit of crossover here between this stage and the reconnaissance phase, but separating them out makes them easier to understand. 

Exploitation

Using the vulnerable entry points highlighted in the previous two phases, the pentester will attempt to gain unauthorised access to the web app’s data. 

From there, they use strategies like privilege escalation to gain higher levels of access within the application through the exploitation of other vulnerabilities.

Post-Exploitation

In this stage, the pentester will attempt to leave the web app without leaving a single trace of having ever been there.

Reporting and Remediation

Finally, the pentester will develop an impact assessment that determines the potential impact of a successful web app cyberattack. 

They will report this alongside an itemised list of vulnerabilities, in order of severity along with remediation advice on how the vulnerabilities should be patched. 

This gives the developers a clear understanding of the attack surface available to hackers, and a strategy for improvement.

Common Web Application Vulnerabilities and the OWASP Top Ten

When talking about the most common and dangerous web application vulnerabilities, there’s no better place to start than the OWASP Top Ten. 

For those that haven’t heard of the OWASP Top Ten, is a widely recognised framework that highlights the most critical web application security risks, including:

• SQL Injection: Exploiting vulnerabilities in database queries.
• Cross-Site Scripting (XSS): Injecting malicious scripts into web pages viewed by users.
• Broken Authentication: Exploiting weaknesses in user authentication mechanisms.

Addressing these vulnerabilities not only strengthens security but also ensures compliance with best practices and standards.

Check out our comprehensive guide to the OWASP Top Ten to learn more.

What are the Benefits of Web Application Penetration Testing?

While we’ve already highlighted all the main benefits throughout this article, this should provide you with a quick overview. It’s also worth noting that the benefits are countless, so we have have narrowed it down to three.

Improve Web App Cybersecurity

Obviously, the main benefit of web app pentesting is that it provides you with the means to significantly improve your web app cybersecurity. 

By identifying and addressing vulnerabilities, developers can significantly reduce their risk of their app being successfully breached by a real-life hacker.

Compliance

By improving your web app cybersecurity, pentests are able to help you meet regulatory requirements and demonstrate a solid commitment to cybersecurity. 

As we like to say, compliance is significantly cheaper than non-compliance.

Build Brand Trust

Successful cyberattacks can completely destroy app usage, since it signals to your user-base that you cannot be trusted to look after their sensitive data. 

By proactively securing your web app, you can build confidence among customers and stakeholders, protecting the business’s reputation.

Common Misconceptions of Web Application Penetration Testing

Much like the benefits, there are far too many to name here, so we’ve picked the most common three.

Pentesters Fix the Vulnerabilities They Find

Don’t get me wrong, we can do, but this isn’t standard practice for several reasons. 

The most important one being, web app developers know the source code better than anyone. By providing them with remediation advice, they will be able to patch these vulnerabilities faster and significantly cheaper than a third-party pentest company. 

Only for Large Organisations

If your app has users, then you are responsible for keeping them and their data safe (not to mention your employees and stakeholders data). With that in mind, assuming that web app pentests are reserved only for large companies is a very dangerous.

If funding is preventing you from carrying out a web app pentest, then the best thing to do is to talk to a company like ourselves where we will be able to help you find something that is helpful and within your budget.

One Time Is Enough

Another dangerous misconception is to assume that one pentest is enough. Things become outdated very quickly and if you don’t keep up, you can put yourself and your customers at risk. On top of that, every major update to you web app could introduce fresh vulnerabilities eithout you realising. 

The best policy is to have at least one web app pentest annually, but if you want to take web app cybersecurity very seriously, you should perform some type of pentest after every major update.

Selecting a Web Application Penetration Testing Provider

Now that you understand what web app pentests are, why they’re important, their benefits and the common misconceptions, all that’s left is to work out how to pick a pentesting company.

The best approach, if you’re in the UK, is to find CREST-certified providers and CREST-qualified pentesters or use CHECK, a list of NCSC-approved (National Cyber Security Centre) penetration test providers.

By picking CREST-certified and NCSC-approaved providers, you significantly increase the trustworthiness and reliability of the pentest provider. 

Conclusion

For web app developers, cybersecurity might seem like a pain because of the associated costs, but it is so important. If you want to build a web app that is safe to use, regular web app pentests are a must.

The last thing you want is to put months, if not years, of your life into developing a web app, only for it to be compromised by a cybercriminal, damaging its credibility and potentially ruining your business.

After all, cybercriminals do not discriminate by the size of the company. If your web app is easy to exploit, that is all that matters to them. 

If you want to book a penetration test for your web application, get in touch today to book a call with one of our expert CREST-qualified pentesters. Or, check out our web application penetration testing service page.