Web Application Security Testing Guide

Effective Web Application Security Testing has become crucial in recent times. Here is a detailed tutorial for website security testing:

Due to the huge amount of data stored in web applications and an increase in the number of transactions on the web, proper Web Application Security Testing is becoming very important day-by-day. In this tutorial, we will provide you with a detailed understanding of the meaning, tools and key terms used in Website Security Testing along with its testing approach.

Let’s move ahead!!

Web Application Security Testing

Web Application Security Testing

What is Security Testing

Security Testing is a process that checks whether the confidential data stays confidential or not (i.e., it is not exposed to individuals/entities for which it is not meant) and the users can perform only those tasks that they are authorized to perform.

For Example, a user should not be able to deny the functionality of the website to other users or a user should not be able to change the functionality of the web application in an unintended way, etc.

Some Key Terms Used in Security Testing

Before we proceed further, it would be useful to familiarize ourselves with a few terms that are frequently used in web application Security Testing.

#1) What is “Vulnerability”?

This is a weakness in the web application. The cause of such “weakness” can be due to the bugs in the application, an injection (SQL/ script code), or the presence of viruses.

#2) What is “URL Manipulation”?

Some web applications communicate additional information between the client (browser) and the server in the URL. Changing some information in the URL may sometimes lead to unintended behavior by the server and this is termed URL Manipulation.

#3) What is “SQL injection”?

This is the process of inserting SQL statements through the web application user interface into some query that is then executed by the server.

#4) What is “XSS (Cross-Site Scripting)”?

When a user inserts HTML/ client-side script in the user interface of a web application, this insertion is visible to other users and it is termed XSS.

#5) What is “Spoofing”?

Spoofing is the creation of hoax look-alike websites and emails.

Recommended Security Testing Tools

#1) Acunetix

Acunetix Banner

Acunetix is an end-to-end web application security scanner. This will give you a 360-degree view of the security of your organization. It is capable of detecting 6500 types of vulnerabilities like SQL injections, XSS, Weak Passwords, etc. It makes use of advanced macro recording technology for scanning complex multi-level forms.

Why do we recommend this tool?

The platform is intuitive and easy to use. You can schedule and prioritize full scans as well as incremental scans. It contains a built-in vulnerability management functionality. With the help of CI tools like Jenkins, new builds can be scanned automatically.

#2) Invicti (formerly Netsparker)

Invicti Banner

Invicti (formerly Netsparker) is a platform for all web application security testing requirements. This web vulnerability scanning solution has capabilities of vulnerability scanning, vulnerability assessment, and vulnerability management.

Why do we recommend this tool?

Invicti is best for scanning precision and unique asset discovery technology. It can be integrated with popular issue management and CI/CD applications.

Invicti provides proof of exploit on the identification of vulnerability to confirm that it is not a false positive. It has an advanced scanning engine, advanced crawling authentication features, and WAF integration functionality, etc. With this tool, you will get detailed scanned results with insights on vulnerability.

#3) Intruder

Intruder Logo

Intruder is a cloud-based vulnerability scanner that performs thorough reviews of your entire tech stack, covering web apps and APIs, single page applications (SPAs), and their underlying infrastructure.

Why do we recommend this tool?

Intruder comes with multiple integrations that speed up issue detection and remediation and you can use its API to add Intruder to your CI/CD pipeline and optimize your security workflow. Intruder will also perform emerging threat scans when new issues arise, saving your team time by automating manual tasks.

By interpreting the raw data drawn from leading scanning engines, Intruder returns intelligent reports that are easy to interpret, prioritize, and action. Each vulnerability is prioritized in context for a holistic view of all vulnerabilities, reducing your attack surface.

Security Testing Approach

In order to perform a useful security test of a web application, the security tester should have good knowledge of the HTTP protocol. It is important to have an understanding of how the client (browser) and the server communicate using HTTP.

Additionally, the tester should at least know the basics of SQL injection and XSS.

Hopefully, the number of security defects present in the web application will not be high. However, being capable of describing all the security defects accurately with all the required details will definitely help.

Methods For Web Security Testing

#1) Password Cracking

The security testing on a Web Application can be kicked off by “Password Cracking”. In order to log in to the private areas of the application, one can either guess a username/ password or use some password cracker tool for the same. A list of common usernames and passwords is available along with open-source password crackers.

If the web application does not enforce a complex password (For Example, with alphabets, numbers, and special characters or with at least a required number of characters), it may not take very long to crack the username and password.

If a username or password is stored in cookies without being encrypted, then an attacker can use different methods to steal the cookies and the information stored in the cookies like username and password.

For more details, see an article on “Website Cookie Testing”.

#2) URL Manipulation Through HTTP GET Methods

A tester should check whether the application passes important information in the query string or not. This happens when the application uses the HTTP GET method to pass information between the client and the server.

The information is passed through the parameters in the query string. The tester can modify the parameter value in the query string to check if the server accepts it.

Via HTTP GET request user information is passed to the server for authentication or fetching data. The attacker can manipulate every input variable passed from this GET request to a server in order to get the required information or to corrupt the data. In such conditions, any unusual behavior by the application or web server is the doorway for the attacker to get into an application.

#3) SQL Injection

The next factor that should be checked is SQL Injection. Entering a single quote (‘) in any textbox should be rejected by the application. Instead, if the tester encounters a database error, it means that the user input is inserted in some query which is then executed by an application. In such a case, the application is vulnerable to SQL injection.

SQL injection attacks are very critical as an attacker can get vital information from the server database. To check SQL injection entry points into your web application, find out the code from your codebase where direct MySQL queries are executed on the database by accepting some user inputs.

If the user input data is crafted in SQL queries to query the database, an attacker can inject SQL statements or part of the SQL statements as user inputs to extract vital information from a database.

Even if an attacker is successful in crashing the application, from the SQL query error shown on a browser, the attacker can get the information they are looking for. Special characters from the user inputs should be handled/escaped properly in such cases.

#4) Cross-Site Scripting (XSS)

A tester should additionally check the web application for XSS (Cross-site scripting). Any HTML For Example, <HTML> or any script For Example, <SCRIPT> should not be accepted by the application. If it is, then the application can be prone to an attack by Cross-Site Scripting.

The attacker can use this method to execute a malicious script or URL on the victim’s browser. Using cross-site scripting, an attacker can use scripts like JavaScript to steal user cookies and information stored in the cookies.

Many web applications get some useful information and pass this information on to some variables from different pages.

For Example, http://www.examplesite.com/index.php?userid=123&query=xyz

The attacker can easily pass on some malicious input or <script> as a ‘&query’ parameter which can explore important user/server data on the browser.

Important: During security testing, the tester should be very careful and should not modify any of the following:

  •  Configuration of the application or the server.
  •  Services running on the server.
  •  Existing user or customer data hosted by the application.

Additionally, a security test should be avoided in a production system.


The purpose of a security test is to discover the vulnerabilities of the web application so that the developers can remove these vulnerabilities from the application and make the web application as well as its data safe from any unauthorized action.

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Feel free to share your comments/suggestions about this tutorial.

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