JavaScript is the core of many websites you see on smartphones and other devices. Despite having a large community of developers and peers, it is not free from potential vulnerabilities. A JavaScript-based website can suffer from man-in-the-middle attacks, cross-site scripting attacks, code injections, and more.

The best way to avoid such attacks is to analyze these vulnerabilities and employ counter-security measures. This article focuses on key JavaScript best practices to avoid vulnerabilities and cyber-attacks.

First, let us understand some key vulnerabilities and cyber threats that JavaScript-based websites can face.

Top vulnerabilities and cyber threats to JavaScript-based websites

Like any other technology, JavaScript has vulnerabilities, which cyber attackers use to exploit websites.

Cross-Site Scripting (XSS)

In XSS cyber-attacks, a hacker injects malicious scripts into websites executed in the browser. It results in data leaks of login information and session cookies.

If a web page generates output using unsanitized user input, it becomes vulnerable to XSS. The browser reads this input, making XSS attacks possible in VBScript, ActiveX, Flash, and even CSS, which is common in JavaScript. Therefore, you must validate user input to ensure JavaScript security.

Cross-Site Request Forgery (CSRF)

CSRF attacks where hackers leverage social engineering practices to trick users into taking specific actions on the website. It allows an attacker to take control of the websites and perform specific actions on behalf of the user without consent.

To reduce the risk of CSRF vulnerabilities, it is important to use protective measures such as CSRF tokens and the SameSite attribute in cookies.

Server-Side Injection

JavaScript injection can happen when untrusted hackers add untrusted data to the server code. This can cause problems like unauthorized access or data leakage. Secure coding practices and input validation are the best way to avoid such unauthorized access.

JSON Hijacking

It is a type of attack where hackers exploit the browser’s policy. Hackers gain unauthorized access to sensitive JSON data. This vulnerability occurs when a website returns a JSON data array instead of using “Content-Type” headers.

Use the “application/json” Content-Type header for JSON responses to prevent JSON hijacking. Another approach is to use prefix the JSON data with “while(1);” to prevent direct script execution.

Insecure Direct Object References (IDOR)

IDOR vulnerabilities occur when an app allows users to access sensitive data without authorization. It leads to unauthorized access and data exposure. To avoid such vulnerabilities, your app must have proper access controls, authorization mechanisms, and input validation to avoid such vulnerabilities.

Man in the middle attacks (MITM)

Man-in-the-Middle (MITM) is a type of cyber-attack where an attacker intercepts and alters the communication between server and browser. MITM can have significant consequences for JavaScript-based websites.

During module installation, attackers can manipulate unencrypted traffic between browsers and the npm registry. This involves exploiting install hooks that download or use resources from the internet over HTTP.

Now that we know what the key JavaScript vulnerabilities are let’s understand key JavaScript security best practices,

Top JavaScript best practices.

Following JavaScript best practices help protect your websites against vulnerabilities and cybersecurity attacks.

#1. Ensure high-quality code

Cyberattacks are mostly executed by exploiting a vulnerability in the source code. A US Department of Home Security report suggests that 90% of computer security incidents are traced back to software code vulnerabilities. So, ensuring high-quality code becomes crucial for your JavaScript security.

Correct use of equality operators, hoisting, and callbacks are crucial to ensure high-quality code thorough understanding of fundamentals. You need to evade functions that assess strings as code, such as eval(), Function(), setTimeout(), and setInterval().

If used with untrusted data, these functions can lead to cross-site scripting (XSS) attacks. You can use a linter, such as ESLint, to identify code issues early. Another way to ensure high quality and secure code is to use static application security testing (SAST).

Further, you can use the strict mode introduced by ECMAScript5. It is one of the JavaScript best practices to convert silent errors into evident errors.

#2. Check whether you need third-party libraries or not!

Third-party libraries are reusable codes that most developers use for rapid development. In JavaScript, many libraries can have vulnerabilities. The best approach is to check the identity of the developers who developed the third-party package, its maintenance status, and if it has any unpatched vulnerabilities.

Ensure you install the correct package because deceptive package names cause JavaScript security issues.

#3. Secure communication between browser and server

A key JavaScript security best practice is to leverage HTTPS for communications between the browser and server instead of HTTP. It secures communication and ensures that the data exchanged remains anonymous to hackers. The next way to ensure an HTTPS-based connection is to install an SSL certificate.

You can buy SSL certificate from leading certificate authorities (CAs) like Comodo, DigiCert, etc. These CAs will ask for a certificate-signing request (CSR) with all the details regarding your organization and verify domain ownership based on the type of certificate you choose.

Once you submit the CSR, CA will verify the information and issue an SSL certificate that you can install on the website. This ensures that the connection between the browser and server is secure whenever a user tries to access data.

#4. Makes sure each input is validated

Hackers often trick browsers into interpreting text input by users into JavaScript code. This is what attackers need to execute XSS attacks. So, validating each text user input on your websites becomes crucial.

Input validations are crucial JavaScript security best practices allowing you to secure apps from code manipulations and other cyberattacks. One way to ensure input validation is efficient is by using encoding practices based on the Open Web Application Security Project (OWASP) recommendations.

Some of the OWASP-recognized encodings that you can use are,

  • HTML entity encoding
  • HTML attribute encoding
  • URL encoding
  • JavaScript string encoding
  • CSS Hex

Further, if your website accepts HTML as user input, sanitize it before displaying it on the page. This includes sanitizing, validating user input, and cleaning all the unexpected characters in the code.

#5. Prevent JSON injections

Developers often use JSON as a reliable syntax to enable information exchange between apps. JSON is a simple syntax and easy to understand with a predictable hierarchical structure. In a JSON injection attack, hackers will supply untrusted data input which lacks validation or sanitization to an app.

Such attacks can affect the server side or client side of the website. Therefore, if you execute a code on the server side to build a JSON object from a string, the concatenating of user input exposes sensitive information to hackers.

TO avoid JSON injections, JavaScript best practice you can use is to validate the user input and stop using functions that evaluate code as strings. For example, you can use JSON.parse() function to parse JSON strings. Further, you can restrict the usage of functions that evaluate code as strings in your security policies.

Key takeaways

Securing your business websites from JavaScript vulnerabilities requires an assessment of vulnerabilities. Once you identify the vulnerabilities and cyber threats, you can use JavaScript best practices to improve the security of websites.

Some of the JavaScript security best practices we discussed include input validations, sanitization, and creating high-quality code. Further, the use of HTTPS is also crucial to ensure better security. All these best practices are effective, but which one to use will depend on the specific requirements of your website.