Front End Security Best Practices

1. Introduction

Front end security is crucial for protecting user data and maintaining the integrity of the application. This lesson discusses key concepts, common vulnerabilities, and best practices to enhance front end security.

2. Common Vulnerabilities

2.1 Cross-Site Scripting (XSS)

XSS attacks allow attackers to inject malicious scripts into webpages viewed by users. This can lead to data theft and session hijacking.

2.2 Cross-Site Request Forgery (CSRF)

CSRF tricks the user into submitting a malicious request that they did not intend to make, potentially compromising their account.

2.3 Insecure Direct Object References (IDOR)

IDOR vulnerabilities occur when an application exposes a reference to an internal object, allowing unauthorized access to sensitive data.

3. Best Practices

3.1 Input Validation

Always validate user inputs on both client and server sides to prevent malicious data entry.

Tip: Use libraries like validator.js for input validation.

3.2 Content Security Policy (CSP)

Implement a CSP to restrict the sources from which scripts can be loaded, thus mitigating XSS attacks.


Content-Security-Policy: default-src 'self'; script-src 'self' https://trusted.cdn.com;

3.3 Secure Cookies

Use HttpOnly and Secure flags on cookies to prevent access to cookie data via JavaScript.

3.4 Sanitization

Sanitize user inputs and outputs to prevent XSS. Use libraries like DOMPurify to clean HTML inputs.


const cleanHTML = DOMPurify.sanitize(dirtyHTML);

3.5 HTTPS

Always use HTTPS to encrypt data in transit, preventing man-in-the-middle attacks.

4. Tools and Resources

OWASP ZAP - A free security scanner for web applications.
Snyk - Tool for finding and fixing vulnerabilities in open source dependencies.
Content Security Policy (CSP) Evaluator - To check CSP implementation.

5. FAQ

What is XSS?

XSS (Cross-Site Scripting) is a vulnerability that allows an attacker to inject scripts into web pages viewed by other users.

How can I prevent CSRF?

Use anti-CSRF tokens in forms and validate them on the server side to prevent unauthorized actions.

What is CSP?

Content Security Policy (CSP) is a security feature that helps prevent XSS and other attacks by controlling the sources from which resources can be loaded.