Skip to content

Latest commit

 

History

History
29 lines (24 loc) · 4.57 KB

attack-surface.md

File metadata and controls

29 lines (24 loc) · 4.57 KB

Attack Surface Analysis for erusev/parsedown

Attack Surface: Cross-Site Scripting (XSS) via Markdown Injection

  • Description: Parsedown's core function of converting Markdown to HTML can be exploited to inject malicious JavaScript. If user-provided Markdown is parsed by Parsedown and the resulting HTML is rendered in a web page without proper output encoding, attackers can inject scripts that execute in users' browsers.
  • Parsedown Contribution to Attack Surface: Parsedown parses Markdown syntax, including HTML tags and attributes. It faithfully translates Markdown into HTML, including potentially malicious HTML injected within the Markdown input. Parsedown itself does not perform automatic sanitization of the generated HTML output against XSS.
  • Example:
    • Markdown Input: [Image with XSS](https://example.com "Title" onerror="alert('XSS')")
    • Parsed HTML (vulnerable): <p><a href="https://example.com" title="Title" onerror="alert('XSS')">Image with XSS</a></p>
    • Impact: Full compromise of user accounts, session hijacking, redirection to malicious websites, theft of sensitive data, website defacement, and propagation of malware.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Mandatory Context-Aware Output Encoding: Always HTML-encode the output generated by Parsedown before displaying it in a web browser. Use appropriate encoding functions provided by your templating engine or framework (e.g., htmlspecialchars in PHP, template escaping in Jinja2/Django). This is the most crucial mitigation.
    • Content Security Policy (CSP): Implement a strict CSP, especially the script-src directive, to limit the sources from which scripts can be executed. This acts as a defense-in-depth measure to reduce the impact of XSS even if output encoding is missed. Avoid using 'unsafe-inline' and 'unsafe-eval' in your CSP.
    • Regular Security Audits and Penetration Testing: Specifically test for XSS vulnerabilities in areas where Parsedown is used to render user-supplied Markdown. Include fuzzing and manual code review to identify potential bypasses or missed encoding instances.

Attack Surface: Vulnerabilities in Parsedown Library Itself

  • Description: Like any software library, Parsedown may contain undiscovered security vulnerabilities within its parsing logic or code. These vulnerabilities could be exploited by attackers if they are discovered and targeted.
  • Parsedown Contribution to Attack Surface: By using Parsedown, your application becomes dependent on its security. Any vulnerability in Parsedown directly translates to a potential vulnerability in your application.
  • Example: Hypothetical scenario: A vulnerability in Parsedown's link parsing logic allows for remote code execution when processing a specially crafted Markdown link. (Note: This is a hypothetical example for illustration; no known RCE vulnerability in Parsedown is being claimed here).
  • Impact: The impact depends entirely on the nature of the vulnerability within Parsedown. It could range from information disclosure and XSS (if the vulnerability allows bypassing output encoding) to remote code execution, leading to complete server compromise and data breaches.
  • Risk Severity: High to Critical (depending on the specific vulnerability discovered)
  • Mitigation Strategies:
    • Proactive Parsedown Updates: Immediately update Parsedown to the latest stable version whenever security updates or bug fixes are released. Monitor the Parsedown GitHub repository and security advisories for announcements.
    • Dependency Scanning and Vulnerability Management: Integrate dependency scanning tools into your development pipeline to automatically detect known vulnerabilities in Parsedown and other dependencies. Establish a process for promptly addressing reported vulnerabilities.
    • Security Monitoring and Incident Response: Implement security monitoring to detect unusual activity that might indicate exploitation of a Parsedown vulnerability. Have a clear incident response plan in place to handle security breaches effectively.
    • Consider Web Application Firewall (WAF): In some cases, a WAF might be able to detect and block certain types of attacks targeting Parsedown vulnerabilities, providing an additional layer of defense. However, WAFs are not a replacement for secure coding practices and dependency management.