JavaScript Interview Questions
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Question 95

Question

What are some common JavaScript security vulnerabilities, and how can they be prevented?

Answer

JavaScript's dynamic nature and client-side execution make it vulnerable to various attacks. Here are some common ones and how to prevent them:

1. Cross-Site Scripting (XSS):

  • The Problem: Attackers inject malicious scripts into websites, which then execute in the browsers of unsuspecting visitors. This can steal data, redirect users to harmful sites, or deface the website itself.

  • Prevention:

    • Input Sanitization: Always validate and escape user input before displaying it on the page. Use appropriate HTML encoding techniques (e.g., textContent instead of innerHTML) for user-provided text.

    • Output Encoding: Encode data properly when sending it to the browser to prevent it from being interpreted as code.

2. Cross-Site Request Forgery (CSRF):

  • The Problem: Attackers trick users into performing actions on a website without their knowledge, using hidden requests sent from a trusted site. This can lead to unauthorized account changes, data transfers, or other malicious actions.

  • Prevention:

    • CSRF Tokens: Use unique, unpredictable tokens generated server-side and included in every form submission. Verify these tokens on the server before processing requests.

3. SQL Injection:

  • The Problem: Attackers exploit vulnerabilities in web applications that use user input to construct SQL queries. Malicious SQL code can be injected to retrieve sensitive data, modify database contents, or even take control of the database server.

  • Prevention:

    • Parameterized Queries: Use parameterized queries (prepared statements) instead of directly embedding user input into SQL queries. This prevents attackers from injecting malicious code.

    • Input Validation & Sanitization: Carefully validate and sanitize all user-provided data before using it in any SQL statements.

4. Session Hijacking:

  • The Problem: Attackers steal a user's session ID (a unique identifier that allows access to their account), enabling them to impersonate the user and perform actions on their behalf.

  • Prevention:

    • Secure Cookies: Use HTTPS for all communication and set cookies with appropriate security flags (HttpOnly, Secure).

    • Session Timeout: Implement session timeouts to automatically invalidate sessions after a period of inactivity.

5. JavaScript Injection:

  • The Problem: Similar to XSS, but focuses specifically on injecting malicious JavaScript code into web pages or applications. This can lead to data theft, script execution, and other exploits.

  • Prevention:

    • Input Validation & Sanitization: Again, crucial! Validate and escape all user input that might be executed as JavaScript code.

Additional Tips:

  • Keep Software Updated: Regularly update your web server software, frameworks, libraries, and browser to patch known vulnerabilities.

  • Implement Access Control: Use role-based access control (RBAC) to restrict user permissions and minimize the potential impact of compromised accounts.

  • Security Testing: Conduct regular security testing, including penetration testing, to identify vulnerabilities in your applications and infrastructure.

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Last updated 9 months ago