JavaScript Security

JavaScript Security is a specialized area of cybersecurity focused on identifying and mitigating vulnerabilities within JavaScript code, which primarily executes on the client-side in a user's web browser. Because this code runs in an environment outside of a developer's direct control, it creates unique attack vectors, with the most prominent being Cross-Site Scripting (XSS), where malicious scripts are injected into trusted websites to be executed by other users. The practice involves implementing defensive measures such as proper input sanitization, output encoding, using Content Security Policies (CSP) to restrict script sources, and securely managing third-party libraries to prevent supply chain attacks, all to protect user data and maintain the integrity of web applications.

1. Fundamentals of JavaScript Security
   1. The Role of JavaScript in Web Applications
      1. Enhancing User Experience
      2. Enabling Dynamic Content
      3. Facilitating Client-Server Communication
      4. Integrating with Third-Party Services
      5. Client-Side Processing and Validation
      6. Real-Time Data Updates
      7. Interactive User Interfaces
   2. The Client-Side Security Model
      1. The Browser as an Execution Environment
         1. JavaScript Engine Overview
         2. Browser Sandboxing Mechanisms
         3. Isolation of Browser Tabs and Windows
         4. Process Isolation Models
         5. Memory Protection Mechanisms
      2. The Same-Origin Policy (SOP)
         1. Definition and Purpose
         2. How Origins are Defined
            1. Protocol
            2. Host
            3. Port
         3. Enforcement of SOP in Browsers
         4. Exceptions and Workarounds
            1. Cross-Origin Resource Sharing (CORS)
            2. Document Domain Relaxation
            3. postMessage API
            4. JSONP (Legacy)
            5. WebSockets Cross-Origin Behavior
      3. Browser Security Architecture
         1. Renderer Process Isolation
         2. Privilege Separation
         3. Site Isolation
   3. The Threat Landscape
      1. Common Attack Vectors
         1. Cross-Site Scripting (XSS)
         2. Cross-Site Request Forgery (CSRF)
         3. Clickjacking
         4. Prototype Pollution
         5. Insecure Data Storage
         6. Supply Chain Attacks
         7. Code Injection
         8. Session Hijacking
      2. The Attacker's Goals
         1. Stealing Sensitive Data
         2. Hijacking User Sessions
         3. Defacing Websites
         4. Spreading Malware
         5. Gaining Unauthorized Access
         6. Cryptocurrency Mining
         7. Botnet Recruitment
      3. Attack Surfaces
         1. User Input Fields
         2. URL Parameters
         3. HTTP Headers
         4. Third-Party Content
         5. Browser Extensions
         6. Local Storage Mechanisms