Skip to content

Latest commit

 

History

History
28 lines (23 loc) · 5.42 KB

attack-surface.md

File metadata and controls

28 lines (23 loc) · 5.42 KB

Attack Surface Analysis for preactjs/preact

Attack Surface: 1. DOM-based Cross-Site Scripting (XSS)

  • Description: Injection of malicious JavaScript code into the Document Object Model (DOM) through user-controlled data, leading to script execution in the user's browser.
  • Preact Contribution: Preact's client-side rendering nature and JSX syntax can make it easy to inadvertently render unsanitized user input directly into the DOM within components. Developers might overlook sanitization needs when dynamically generating UI elements based on data. The framework's focus on developer experience and ease of use might sometimes lead to overlooking security best practices like explicit sanitization, especially for developers new to front-end security.
  • Example: An application displays user-generated blog posts. If a blog post title containing <img src=x onerror=alert('XSS')> is rendered by Preact without sanitization, the JavaScript alert('XSS') will execute when a user views the post.
  • Impact: Session hijacking, cookie theft, user redirection to malicious sites, defacement of the application, data theft, and potentially full account takeover.
  • Risk Severity: High to Critical
  • Mitigation Strategies:
    • Input Sanitization: Sanitize all user-provided data and data from untrusted sources before rendering it in Preact components. Utilize browser built-in functions like textContent or robust sanitization libraries like DOMPurify to escape or remove potentially harmful HTML tags and JavaScript code.
    • Content Security Policy (CSP): Implement a strict CSP to control the sources from which the browser is allowed to load resources. This significantly limits the impact of XSS by preventing execution of inline scripts and scripts from untrusted origins, even if injection occurs.
    • Use Preact's dangerouslySetInnerHTML with Extreme Caution (and ideally avoid): Minimize or completely avoid using dangerouslySetInnerHTML. If absolutely necessary for specific use cases (like rendering truly trusted, pre-sanitized HTML content), ensure the data is meticulously sanitized using a highly reputable and actively maintained library like DOMPurify before passing it to dangerouslySetInnerHTML. Treat this feature as a last resort and thoroughly document its usage and sanitization procedures.
    • Regular Security Audits and Penetration Testing: Conduct frequent security audits and penetration testing, specifically focusing on identifying and remediating potential XSS vulnerabilities within Preact components and data rendering logic.

Attack Surface: 2. Server-Side Rendering (SSR) Rehydration Mismatches leading to Security Issues

  • Description: Inconsistencies between server-rendered HTML and client-rendered DOM during rehydration can create vulnerabilities if data handling is not synchronized and secure across both environments.
  • Preact Contribution: Preact's SSR implementation, while enhancing performance and SEO, introduces complexity in managing data flow between server and client. Subtle differences in how data is processed or sanitized during server-side rendering versus client-side rehydration, especially within Preact components, can lead to security gaps. The framework's SSR features require developers to be acutely aware of data consistency across environments.
  • Example: A dynamic e-commerce site uses SSR. Product descriptions containing potentially malicious HTML are rendered on the server without sanitization for performance reasons. Client-side sanitization is intended to occur after rehydration. However, a race condition or error during rehydration could leave the unsanitized server-rendered HTML active for a brief period, potentially allowing XSS before client-side sanitization kicks in.
  • Impact: Bypass of client-side security measures, potential for XSS if server-rendered content is not properly sanitized, unexpected application behavior, and data integrity issues.
  • Risk Severity: High
  • Mitigation Strategies:
    • Consistent and Early Sanitization: Prioritize sanitizing user-provided or untrusted data on the server-side before rendering HTML for SSR. Re-sanitize on the client-side as well as a defense-in-depth measure, but rely primarily on server-side sanitization for SSR scenarios.
    • Robust Data Serialization and Deserialization: Implement secure and reliable data serialization and deserialization processes between server and client. Ensure data integrity and prevent any unintended modifications or bypasses during data transfer.
    • Thorough SSR and Rehydration Testing: Rigorously test the application's SSR and rehydration process, specifically focusing on handling dynamic data and user input. Use automated testing and manual security reviews to identify and eliminate any potential rehydration-related vulnerabilities or inconsistencies in data handling.
    • Minimize Client-Side Logic Before Rehydration (for security-sensitive operations): Reduce or eliminate security-sensitive client-side logic that executes before rehydration is fully complete. Ensure that critical security measures are applied consistently and reliably across both server and client environments, ideally starting on the server.