The Best Practices for JavaScript Security

Introduction to JavaScript Security

In September 2018, British Airways, one of the world’s leading airlines, experienced a severe cyber attack. The company’s website was
compromised by a group that called themselves “Magecart.” The hackers exploited a JavaScript vulnerability on the payment page. Consequently, about 380,000 customers fell victim to this hacking incident, where their personal and financial data was stolen. This
JavaScript breach event perfectly exemplifies how insecure JavaScript can be. It is an excellent example that should make you rise on your feet
and bolster your JavaScript Security.

According to a 2022 StackOverflow survey report, JavaScript is used by 67.9% of professional developers. Its extreme usage and adoption underscore its ubiquity in the digital world. Nevertheless, despite JavaScript’s extensive adoption, it regrettably poses a substantial security concern. Safeguarding JavaScript code holds paramount importance, as it directly influences the dependability of enterprises and the confidentiality and confidence of innumerable global users.

In this article, you will gain valuable knowledge on effective techniques and fundamental principles to fortify your JavaScript code, fostering a more resilient online landscape.

Understanding JavaScript Vulnerabilities

JavaScript, an amazingly powerful and versatile web development language, has vulnerabilities. Understanding these vulnerabilities and
how they work puts you in the right spot to protect yourself against them. The path to secure JavaScript coding begins with awareness, vigilance, and a commitment to best practices.

A critical risk area lies in its strength: the ability to interact dynamically with webpage content. One major JavaScript vulnerability you must be aware of is Cross-Site Scripting (XSS) attack, which can be quite problematic. In such attacks, crafty hackers inject harmful scripts into
valid web pages, only to have them executed by unsuspecting users. Cross-Site Request Forgery (CSRF) is a noteworthy susceptibility that demands sincere consideration. This method encompasses the art of misleading end users into inadvertently executing actions that were never part of their intentions, jeopardizing their data’s security and making it susceptible to theft or tampering. It’s crucial to stay vigilant against such threats.

Inadequately secured JavaScript code can also be exploited through code injection, often via indiscriminate functions like eval(). Importantly,
third-party scripts present a significant risk. Many websites rely on external scripts for functionality, but they can serve as a gateway for attackers if they are compromised.

JavaScript Security Practices

As JavaScript’s prevalence continues to rise, the risk for an app regarding JavaScript Security is rising. This section discusses some essential practices to help ensure your JavaScript code remains impervious to various threats.

Implement Secure Code Practices

Writing secure JavaScript code isn’t just about syntax but understanding potential pitfalls and loopholes that can be exploited. Start with comprehensive education about common security risks, including Cross-Site Scripting (XSS) and code injection. Ensure that code is written following best practices such as validating input, sanitizing output, and correctly managing errors. Consider implementing a linter in your development process to catch issues like the unsafe use of eval() and to enforce style consistency. Encourage regular peer code reviews; they offer opportunities for learning and catching security issues that automated tools may miss. Above all, foster a security-focused culture within your development team, where writing secure code becomes second nature.

Use HTTPs for Secure Communication

Communication between client and server must be secure to prevent eavesdropping or data tampering. Transitioning from HTTP to HTTPS plays a pivotal role in achieving secure communication. HTTP is an insecure protocol because it lacks encryption strengths. On the other hand, HTTPS utilizes SSL/TLS protocols to establish secure communication channels. HTTPS comes with immense encryption power to safeguard the privacy and integrity of data. It is necessary to have an SSL certificate to start the website with HTTPS instead of HTTP. A site holder should buy SSL certificate from reputed certificate authority. This certificate also serves as evidence of your website’s identity, enhancing user confidence. Remember, every page and every resource of your website should use HTTPS, not just pages that handle sensitive data. Modern browsers now flag websites without HTTPS as insecure, warning users before they proceed, which could lead to loss of traffic and trust.

Content Security Policies (CSP)

CSP is a powerful security standard that helps protect a site against XSS and data injection attacks. When you establish a content security policy, you specify a roster of reliable origins that a browser can access for loading resources like scripts and images. By employing CSP, you fortify your webpage against potential threats, as the browser will only execute scripts if their sources are included in the approved list. To implement CSP, you need to incorporate a distinct HTTP header (Content-Security-Policy) in your server responses, including the policy itself as its value.
Remember that developing an effective CSP may require a deep understanding of your application’s resource-loading patterns. A too-
strict policy might break your application, while a too-lax one might leave room for attacks.

Avoid Using eval()

The eval() function in JavaScript is a powerful but potentially dangerous tool, as it executes the code it’s given with the privileges of the caller. This could lead to various attacks if an attacker can influence the input to eval(). For instance, they might run arbitrary commands, leading to code injection attacks. To write secure JavaScript code, it’s best to avoid using eval(). If it’s impossible to remove, ensure that the input passed to eval() is not controlled by the user or thoroughly sanitize it to remove any potentially harmful commands. Also, consider using alternatives to eval(), such as JSON.parse for parsing JSON or using function constructors for generating functions from strings.

Defend Against Cross-Site Scripting (XSS)

XSS stands as a persistent weakness within JavaScript-based web applications, denoting a continuing susceptibility. When an XSS attack
occurs, an unauthorized individual inserts harmful scripts into web pages that are being viewed by unsuspecting users. These scripts can retrieve sensitive information such as cookies, session tokens, and other confidential data stored within the browser and utilized by the specific website. Effectively countering XSS requires the adoption of several security measures.
One such measure involves the careful sanitization of user input, which ensures that user data is thoroughly checked before being integrated into a web page. Additionally, implementing HTTP-only cookies can be considered to prevent their exposure to JavaScript, and the application of Content Security Policies (CSP) can help obstruct the execution of
unauthorized scripts.

Update Libraries and Dependencies

JavaScript projects often rely heavily on third-party libraries and packages. These dependencies, if not regularly updated, can become
security vulnerabilities themselves. An outdated library might have unpatched security flaws that attackers can exploit. Ensure you regularly update your dependencies and remove unused libraries to reduce the attack surface. Tools like npm audit or GitHub’s Dependabot can be used to identify and fix insecure dependencies. Additionally, when choosing libraries, favor actively maintained ones with a large user base.
They will likely have fewer security issues and, if discovered, will be promptly patched.

Perform Regular Security Testing and Audits

Ensuring the reliability of your JavaScript code requires a steadfast approach to security testing. Employing automated testing tools, like
static analysis tools, can effectively identify prevalent security concerns. Nevertheless, it is crucial to recognize that they should not serve as the sole means of safeguarding your code’s integrity.
Manual code review is crucial for catching more subtle or complex security vulnerabilities. Consider regular security audits to examine your application from an attacker’s perspective. Make security testing a routine part of your development and deployment process. Consider adopting a DevSecOps approach, integrating security practices into the DevOps process. This approach ensures that security considerations aren’t just an afterthought but an integral part of the entire software development life cycle.

Conclusion

The popularity of JavaScript is on the rise, and the accompanying security risks are also increasing. In the present time, it is crucial to
familiarize oneself with certain security weaknesses linked to JavaScript. Learning about effective measures to ensure JavaScript security is
imperative, as it plays a pivotal role in maintaining one’s safety. This article has provided you with the seven most effective JavaScript
security measures. Implementing them will keep you safe from any associated vulnerabilities.