Everything You Need to Know About JavaScript Security


These days, JavaScript is one of the more well-known and established programming languages around. JavaScript is mostly found in the code of dynamic web pages that allow for extended JavaScript functionalities. These functionalities include useful operations such as interactivity, tracking user activities, and form submission or validation. Although JavaScript is generally regarded as a reasonably safe coding language, many users are growing skeptical about certain aspects of JavaScript security.

Many well-known JavaScript vulnerabilities can affect both the server-side and client-side. Malicious hackers can utilize these vulnerabilities by traversing a number of open paths through your application. When utilizing JavaScript in your application, it is critical to evaluate all JavaScript Security threats seriously and  implement an open source vulnerability scanner to find these threats. 

This article will detail two of the most severe potential JavaScript security vulnerabilities and how to deal with them appropriately. 

Cross-Site Scripting (XSS) Attacks: What Are They?

One of the most common browser-side vulnerabilities is called “Cross-Site Scripting.” Also known as XSS, Cross-Site Scripting attacks happen in client-side scripting languages such as JavaScript or HTML and manipulate an internet security weak spot. When performing an XSS attack, hackers can use legitimate web applications to perform malicious tasks by harnessing a vulnerability.  

XSS attacks are, unfortunately, all too common and can result in the theft of one’s data or identity. These attacks can also result in the spread of the virus across the network by gaining control of the user’s browser. 

Hackers and malicious actors are able to manipulate insecurities on a website. This attack is performed by injecting JavaScript code into the parameters of the site, then using this exploit to gain access to the user’s data. Essentially, this code allows the hacker to transfer ownership of the victim’s session ID to that of the hacker to take control of the browser. 

How can it be prevented? 

There are several ways to ensure that your JavaScript is safe and secure:

  • First, you must filter all input as it arrives. This means that whenever a user provides input, there needs to be a strict filter to compare it to what is generally assumed to be valid input.
  • Utilize appropriate and effective response headers. In order to prevent an XSS attack from HTTP from responses that are supposed to contain any HTML, it is possible to use X-Content-Type-Options or Content-Type option in the headers. These headers will make sure that the browser is responding in the way that it was intended to and is not being exploited. 
  • You should also encode your data when it is being outputted. When a user’s data is outputted in an HTTP response, the output should be encoded to prevent it from being identified as active content.
  • Lastly, be sure to use a Content Security Policy. If you have a CSP set up to the right set of rules, you will be able to prevent the browser from executing any unwanted operations or any JavaScript code that may come from an untrusted source.

Cross-Site Request Forgery (CSRF) Attacks: What Are They?

An XSRF or CSRF is a well-known attack in which the hacker attempts to impersonate or completely take over the identity of the victim by hijacking their active session cookie. This attack is possible when the target site attempts to authenticate a request by only using cookies, which will allow the hacker to gain access or hijack the functional cookies, to appear to be a legitimate user. 

This attack can be very harmful to the victim and can lead to fraud, account tampering, or data theft. The most common targets are popular web applications such as social media, web interfaces, online banking, and in-browser email clients. 

Let us use the online banking situation as an example. 

Most banking websites use active session cookies in order to authenticate any user requests. These cookies then follow the order of events to log into the banking account, enter the valid details needed, then click on the transfer button. 

When a user logs into the account, the banking website will store a session cookie that it will refer back to in order to authorize the transactions. 

The Hack

In order to initiate the hack itself, the hacker would need to create a website that looks legitimate but has an underlying agenda. For this example, we will use a blogging website. If the user logs in and wants to create a new blog post, the malicious application running in the background will then send a “GET” request out to the banking website. This hack is only useful when the user is also logged into the banking site. If they are, the session tokens will be active and in place.

The hacker will then manipulate the “GET” request in order to operate the banking site stealthily. Once the user clicks on the button to add a blog post, they will also unwittingly transfer money to the hacker’s account.

How can it be prevented?

  • You must always utilize SameSite Cookie Attribution when working with session cookies. 
  • The site must also verify both the Referrer Header or Origin.
  • Try to implement any user interaction that is based on protection, especially for highly sensitive procedures like banking. User interaction based on protection should include a re-authentication (usually a password), a CAPTCHA, or even a one-time token. These steps can be strong defenses against a CSRF attack if they are used correctly. 

JavaScript security is a topic that is not often talked about; however, it is highly essential to many professions. Learning to execute JavaScript safely and correctly is not something that most people are able to learn overnight. 

When you are looking to test or upgrade your JavaScript security, it is highly recommended to seek the help of a certified professional or cyber security specialist. These professionals will give you a better and more detailed understanding of your security risks and what actions you can take to correct them. Taking the security of your website seriously is no easy task and requires constant maintenance. However, if you take precautions, your users will be able to browse knowing they are using a safe and secure site.