JavaScript Injection Tutorial: Test and Prevent JS Injection Attacks on Website

An Overview of JavaScript Injection

JavaScript is a commonly employed technology for web applications and websites, providing an array of functionalities. Nonetheless, it carries security hazards that need to be understood by testers and developers.

Even though JavaScript is typically utilized for authentic reasons, it can also be exploited for malevolent attacks such as JavaScript Injection. This entails embedding JavaScript code that is executed on the client-side.

This tutorial delves into how to identify potential JavaScript Injection, the techniques used for executing JS Injection, and the potential repercussions of these attacks.

JavaScript Injection Risks

JS Injection offers several venues for nefarious users to alter a website’s design, gain access to its data, manipulate information displayed, and tamper with parameters like cookies. The resulting damage, potential data breaches, and possible hacking could be serious.

The primary aim of JS Injection is to change the appearance of the website and manipulate parameters. The damage varies, from affecting the website’s design to compromising user accounts.

Why Testing JS Injection is Crucial

The importance of testing for JS Injection vulnerabilities can’t be overstated.

Testing for JS Injection vulnerabilities is a vital aspect of security testing. Although it might require additional effort and time, it’s imperative to incorporate security testing into project planning to ensure a thorough examination of potential attacks.

In order to save project implementation time, teams frequently ignore testing against different attack vectors, including JS Injection. This often leads to complaints and problems for customers later.

Even if it’s not explicitly outlined in project plans, conducting security testing, including evaluations for JS Injection vulnerabilities, is strongly advised. Overlooking simple JavaScript Injection vulnerabilities can have negative effects on product quality and the reputation of your company. Always prioritize testing against potential attacks, including JS Injection, to guarantee a high-quality product.

Comparing with Other Attacks

It’s worth noting that JS Injection is less risky than SQL Injection, as it runs on the client-side and doesn’t directly target the database of the system like SQL Injection attacks. In addition, it’s not as severe as XSS (Cross-Site Scripting) attacks.

While JS Injection primarily impacts the website’s design, XSS attacks are designed to exploit vulnerabilities and steal user login data.

But despite these differences, JS Injection can still inflict substantial damage on a website, such as changing the website’s appearance or laying groundwork for compromising user login information.

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Suggested Tools

#1) Acunetix

Acunetix is an all-encompassing web application security scanner that can detect more than 7,000 vulnerabilities, such as weak passwords, exposed databases and out-of-bound vulnerabilities.

Acunetix is capable of scanning diverse arrays of web pages, web applications and complex web software built with JavaScript and HTML5. It offers quick scanning and verifies the legitimacy of identified vulnerabilities. The software makes use of advanced macro recording technology and provides automation functionalities which include scheduling scans, managing issues, prioritizing scans and performing automatic scans of new iterations.

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#2) Netsparker

Netsparker provides a highly customizable and automated web application security scanner for identifying security weaknesses in web services, web applications, websites and more. It provides proof of identified vulnerabilities by exploiting them in a safe and read-only mode.

Netsparker can identify all types of SQL injection and can detect JavaScript files that are embedded. It supports security professionals by listing all JavaScript files in the Knowledge Base panel for security checks.

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Detecting JavaScript Injection

The initial stage in testing for JS Injection is to ascertain if injection is feasible. This can be effortlessly checked by inputting the following code into the browser’s address bar:

javascript:alert(‘Executed!’);

If a popup window appears with the message “Executed!”, it signals that the website is vulnerable to JS Injection.

In addition, different Javascript commands can be examined by inputting them into the website’s address bar.

Notably, JS Injection is not solely limited to the address bar; other components of a website might be susceptible too. Knowing which areas of a website are vulnerable to Javascript Injection and how to test them is crucial.

The most common targets for JS Injection include:

• Diverse forums
• Comment fields in articles
• Guestbooks
• Any other forms where text can be inserted

In a text-saving form, you can test for this attack by injecting Javascript code instead of common text and saving it. If a text-box appears with the message “Executed!” after refreshing the page, it means the tested form is vulnerable to this attack.

If both methods result in a text box with the message, more advanced measures of JS Injection, such as design manipulation or parameter modification, could be tried out.

It’s important to bear in mind that parameter modification poses more risk than design modification. Consequently, testing for vulnerabilities in parameter modification should be granted extra attention.

Furthermore, remember that fields where any type of data can be inputted are often more vulnerable to Javascript Injection.

Modifying Parameters

As mentioned earlier, one potential damage caused by JS Injection is the modification of parameters.

This attack could be exploited by malicious users to get parameter information or modify parameter values like cookie settings. This poses serious risks as sensitive content may be compromised. Various Javascript commands can be employed to execute this injection.

For example, a Javascript command to retrieve the current session cookie would look like this:

javascript: alert(document.cookie);

When this command is entered into the browser’s URL bar, a popup window with the current session cookies will appear.

If cookies are used by the website, sensitive information like other user data stored in cookies or server session IDs can be retrieved.

Note that the alert() function can be substituted with other Javascript functions.

For instance, say a vulnerable website stores the session ID in the cookie parameter ‘session_id’, a function to change the current session ID can be written as follows:

javascript:void(document.cookie=”session_id=<<other session ID>>”);

This successfully alters the session ID value. Similar methods can be employed for changing other parameter values.

For instance, a malicious user may want to impersonate someone else. To do this, the user first changes the authorization cookie setting to true. If the authentication cookie value isn’t set to “true,” it might return as “undefined”.

To modify cookie values, a malicious user can run the following Javascript command in the browser’s URL bar:

javascript:void(document.cookie=”authorization=true”);

As a result, the current cookie parameter “authorization=false” is replaced with “authorization=true”. This allows the nefarious user to gain access to sensitive information.

Moreover, sensitive information can be exposed by Javascript code.

javascript:alert(document.cookie);

To illustrate, if precautions aren’t taken by a website developer, this code may also return the usernames and passwords parameter names and values. This information could be used to hack the website or modify sensitive parameter values.

For instance, to change the username value, the following code can be run:

javascript:void(document.cookie=”username=otherUser”);

This method can also be used to change the value of any other parameter.

Modification of a Website’s Design

Javascript can also be used to modify the form and general design of a website.

To illustrate, Javascript can be used to alter information displayed on the website, including:

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ul>

Text content

Website’s background

Form’s aesthetic

Popup window’s appearance