Web applications are complex systems with unique security challenges. They're built using a three-tier architecture: client-side, server-side, and database. Each tier has its own vulnerabilities that hackers can exploit.

To protect web apps, developers use various security mechanisms. These include browser-based measures like same-origin policy, server-side controls like input validation, and encryption techniques to safeguard data in transit and at rest.

Web Application Architecture

Three-Tier Architecture and Components

• Three-tier architecture divides web applications into client-side, server-side, and database tiers
• Client-side tier handles user interface and interaction through web browsers or mobile apps
• Server-side tier processes requests, implements business logic, and manages application functionality
• Database tier stores and retrieves data, ensuring persistence and data integrity
• Three-tier architecture enhances scalability, maintainability, and security of web applications

Communication Protocols and Technologies

• HTTP (Hypertext Transfer Protocol) facilitates communication between clients and servers
• HTTPS (HTTP Secure) encrypts data transmission, protecting sensitive information
• RESTful APIs enable standardized communication between client and server components
• WebSockets allow real-time, bidirectional communication for dynamic web applications
• AJAX (Asynchronous JavaScript and XML) enables asynchronous data exchange without page reloads

Client-Side Technologies and Frameworks

• HTML (Hypertext Markup Language) structures web page content
• CSS (Cascading Style Sheets) defines the visual presentation of web pages
• JavaScript enables interactive and dynamic client-side functionality
• Front-end frameworks (React, Angular, Vue.js) streamline development of complex user interfaces
• Progressive Web Apps (PWAs) combine web and native app features for enhanced user experience

Web Security Mechanisms

Browser-Based Security Measures

• Same-origin policy restricts web page scripts from accessing resources from different origins
• Cross-Origin Resource Sharing (CORS) allows controlled access to resources from different origins
• Content Security Policy (CSP) mitigates cross-site scripting (XSS) and other injection-based attacks
• Subresource Integrity (SRI) ensures the integrity of externally loaded resources
• HTTP Strict Transport Security (HSTS) enforces secure connections to prevent downgrade attacks

Server-Side Security Mechanisms

• Web Application Firewall (WAF) filters and monitors HTTP traffic to protect against web-based attacks
• Input validation and sanitization prevent injection attacks and ensure data integrity
• Authentication mechanisms verify user identities (password hashing, multi-factor authentication)
• Authorization controls manage user access to resources and functionalities
• Session management securely handles user sessions to prevent session-based attacks

Encryption and Data Protection

• Transport Layer Security (TLS) encrypts data in transit between client and server
• Database encryption protects sensitive information at rest
• Tokenization replaces sensitive data with non-sensitive equivalents for enhanced security
• Key management systems securely store and manage cryptographic keys
• Data masking conceals sensitive information in non-production environments