JavaScript is a popular programming language for web application development among developers due to its flexibility, interactivity, and user experience. A Stack Overflow survey shows that over 67% of developers use JavaScript, and over 95% of websites use this language.
But from a security perspective, JavaScript is the fourth-most-vulnerable programming language, just behind Java, PHP, and C. Much can go wrong with JavaScript, from malicious attacks to insecure user inputs.
The potential risks include stealing a user’s session, redirecting a session, modifying data, and tricking users into performing unintended actions. JavaScript’s source code vulnerabilities also allow for data exploitation. How can you address these JavaScript vulnerabilities and make your web applications secure in 2022 and next year?
Below is the list of common JavaScript vulnerabilities and how they can steal or manipulate your data:
As JavaScript is an interpreted language rather than a compiled one, a single obfuscation method won’t protect your application against hackers.
Other vulnerabilities include developers’ widespread use of libraries and software packages in the application code. Potential hidden vulnerabilities in the packages can allow hackers to exploit the code later.
How JavaScript interacts with the Document Object Model (DOM) on a web page can pose a security concern, allowing scripts to be embedded and executed on client computers across the Internet.
XSS attacks allow web applications to accept unintended or untrusted scripts on a webpage without proper validation.
The XSS attack involves the hacker interacting with the user through reverse engineering or requesting that they visit a particular page. Next, the browser executes the untrusted script, and the attack completes successfully.
Injection attacks are more common on the server side. They exploit SQL database query parameters to execute arbitrary JavaScript code within an application.
Applications that commonly use string functions such as setTimeout(), eval(), and setInterval() are more vulnerable to injection attacks. An attacker can create an ID string parameter to retrieve all tables from or write to the database.
The client-side JavaScript in a browser accepts all content returned by a web application. This also includes cookies containing sensitive data, such as users’ session IDs. A common way for an XSS attack is to intercept the session ID and send it to the hacker, who can then hijack the session.
There are several preventive measures you can take to reduce vulnerabilities and improve JavaScript application security.
Audit your application code regularly to find potential vulnerabilities. In addition, write test units to ensure your code behaves as you expect and executes securely.
Also, use scanning tools to regularly scan your application code and identify potential vulnerabilities in third-party libraries and packages. So, you can remove them before they can be exploited. Do a regular patch and update your libraries.
To prevent XSS attacks, properly validate and sanitize user input to ensure it contains only acceptable characters. For example, you can allow the phone number field to include only numbers and a dash or parentheses.
Don’t allow unexpected character input. Use methods such as innerText to manipulate the DOM securely. This method escapes malicious content, thus preventing DOM-based XSS attacks.
To prevent malicious SQL injections, you must also perform input validation. If the test fails, the SQL query won’t be executed. Another way to deter potential injection attacks is to replace concatenations with prepared statements or parameterized queries.
Parameterized queries can extract SQL syntax from input parameters.
An excellent way to enhance server-side security is to use server application protection. It will integrate seamlessly with your JavaScript application to prevent active and passive attacks.
Any XSS attack relies on input data containing special characters in the underlying JavaScript. The browser treats these characters as part of the web page code rather than as values to display during execution.
This enables the hacker to escape the text field and provide extra browser-side code for execution. To prevent this type of attack, replace the special characters with an escape code any time your browser-supplied user input returns a response.
For instance, replace the < and > characters with < and > to delimit HTML entities. This will prevent the browser from interpreting these characters as HTML entities, forcing it to display them.
Exposing session IDs in logs, error messages, or URLs is a bad security practice. This causes issues like session hijacking, fixation, and cross-site request forgery (CSRF). The CSRF attack tricks the browser into executing malicious requests to other websites in the background by using the client’s session cookies.
A technique to prevent this attack is to introduce tokenization for client-server interaction. Upon establishing a session, a token must be generated for each form on the site and sent with each request while the user is on the website.
Another way to secure cookie transmission is to use HTTP-only cookies. This attribute prevents the browser from providing access to cookies via the DOM. It will also prevent client-side script attacks from accessing session IDs from the cookies.
JavaScript is a popular programming language, but its source code is visible to anyone with a browser. It also has other potential pitfalls. The recommended best practices for JavaScript security to prevent hackers from exploiting JavaScript vulnerabilities are to keep both the client and server sides secure.
This approach prevents the risk of malicious content while validating the client to improve end-user results. Client-side validation informs users of issues with their input, while server-side validation ensures that only trusted data reaches the JavaScript application.
A good security practice is to obfuscate your JavaScript code to prevent hackers from reverse-engineering, finding vulnerabilities, or debugging it.
JSDefender can help you obfuscate your code, making it difficult for malicious attacks to exploit JavaScript security and modify or steal it. Register today to get a free trial!