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attack-surface.md

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Attack Surface Analysis for tryghost/ghost

Attack Surface: Admin Panel Brute-Force Attacks

  • Description: Attackers attempt to guess administrator credentials for the Ghost admin panel (/ghost) through repeated login attempts.
  • Ghost Contribution: Ghost provides the admin panel and its authentication mechanism. Default Ghost installations might lack built-in robust rate limiting or account lockout specifically for the admin login, making it vulnerable if infrastructure-level protections are missing or misconfigured.
  • Example: An attacker uses a bot to repeatedly try common passwords against the Ghost admin login page, eventually gaining access to an administrator account.
  • Impact: Unauthorized admin access, full website control, content manipulation, data theft, server compromise.
  • Risk Severity: High
  • Mitigation Strategies:
    • Ghost Users/Developers:
      • Enforce Strong Admin Passwords: Mandate strong, unique passwords for all Ghost administrator accounts.
      • Implement Multi-Factor Authentication (MFA): Utilize MFA for Ghost admin logins via plugins, external services, or infrastructure-level solutions compatible with Ghost.
      • Infrastructure Rate Limiting: Configure rate limiting specifically for the /ghost login path using a reverse proxy (like Nginx, Apache) or a Web Application Firewall (WAF) in front of Ghost.
      • Infrastructure Account Lockout: Implement account lockout policies at the infrastructure level to block IP addresses after multiple failed login attempts to the Ghost admin panel.

Attack Surface: Cross-Site Scripting (XSS) in Ghost Themes

  • Description: Attackers inject malicious scripts into a Ghost website through vulnerabilities within custom or third-party themes. These scripts execute in visitors' browsers.
  • Ghost Contribution: Ghost's theme system allows for custom themes, which, if poorly developed, can introduce XSS vulnerabilities. Ghost's templating engine (Handlebars) requires secure usage within themes.
  • Example: A vulnerable Ghost theme fails to properly sanitize user comments, allowing an attacker to inject a script that steals session cookies from users viewing the comment section.
  • Impact: User account compromise, data theft, website defacement, malware distribution to website visitors.
  • Risk Severity: High
  • Mitigation Strategies:
    • Ghost Theme Developers:
      • Secure Theme Coding Practices: Adhere to secure coding principles when developing Ghost themes, especially when handling user-generated content or dynamic data.
      • Utilize Ghost's Sanitization Helpers: Employ Ghost's built-in helpers and security features within themes to properly sanitize and encode user inputs before rendering them.
      • Regular Theme Security Audits: Conduct security reviews and testing of Ghost themes to proactively identify and remediate XSS vulnerabilities.
    • Ghost Users:
      • Choose Reputable Themes: Select themes from trusted sources and developers known for security-conscious development.
      • Keep Themes Updated: Regularly update Ghost themes to the latest versions to benefit from security patches and improvements.

Attack Surface: Server-Side Template Injection (SSTI) in Ghost Themes

  • Description: Attackers inject malicious code into server-side templates within Ghost themes. This code is then executed by the Ghost server, potentially leading to full server compromise.
  • Ghost Contribution: Ghost themes utilize the Handlebars templating engine. Incorrect handling of user input within theme templates can create SSTI vulnerabilities if developers bypass proper escaping or sanitization.
  • Example: A poorly coded Ghost theme directly embeds a blog post title into a Handlebars template without sanitization. An attacker crafts a malicious title containing Handlebars code that, when rendered by Ghost, executes arbitrary commands on the server.
  • Impact: Remote code execution (RCE), complete Ghost server compromise, data breach, denial of service.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Ghost Theme Developers:
      • Strictly Avoid Direct User Input in Templates: Never directly embed user-provided input into server-side templates without rigorous sanitization and validation.
      • Secure Handlebars Templating: Follow secure templating practices specific to Handlebars within Ghost themes to prevent SSTI.
      • Thorough Theme Code Reviews: Implement comprehensive code reviews for Ghost themes, specifically looking for potential SSTI vulnerabilities.
      • Input Validation Before Templating: Validate and sanitize all user inputs before they are passed to the Handlebars templating engine.
    • Ghost Users:
      • Use Trusted Themes: Prioritize themes from reputable sources and developers with a strong security track record.
      • Maintain Theme Updates: Keep Ghost themes updated to receive security fixes and improvements.

Attack Surface: Unrestricted File Uploads via Ghost Media Library

  • Description: Attackers upload malicious files through the Ghost media library due to insufficient file type validation or security controls.
  • Ghost Contribution: Ghost's built-in media library feature allows file uploads. Weaknesses in Ghost's default file upload handling or configuration can lead to vulnerabilities.
  • Example: An attacker bypasses client-side file type checks and uploads a malicious executable file disguised as an image through the Ghost media library. If server-side validation is also weak, this file could be stored and potentially executed, leading to server compromise.
  • Impact: Remote code execution, website defacement, malware hosting, data breach, denial of service (via storage exhaustion).
  • Risk Severity: High
  • Mitigation Strategies:
    • Ghost Users/Developers (Ghost Configuration & Infrastructure):
      • Robust Server-Side File Type Validation: Implement strong server-side file type validation based on file content (magic numbers) and not solely on file extensions within Ghost's upload handling or the infrastructure.
      • Enforce File Size Limits in Ghost/Infrastructure: Configure file size limits within Ghost settings or at the infrastructure level to prevent denial-of-service attacks through large file uploads.
      • Secure File Storage Configuration: Ensure uploaded files are stored outside the web root or in a dedicated storage service. Configure the web server to prevent execution of scripts from the Ghost media upload directory (e.g., using web server configurations).
      • Implement Content Security Policy (CSP): Deploy a strong CSP to limit the impact of potential file upload vulnerabilities by restricting script execution and resource loading.

Attack Surface: API Key Compromise for Ghost Content API

  • Description: Attackers gain unauthorized access to Ghost Content API keys, allowing them to bypass authentication and potentially access content or exploit API vulnerabilities.
  • Ghost Contribution: Ghost's Content API relies on API keys for authentication. Insecure handling or exposure of these keys weakens the API's security.
  • Example: A Ghost user inadvertently exposes a Content API key in client-side JavaScript code. An attacker extracts this key and uses it to scrape all content from the Ghost website or potentially exploit other API endpoints if authorization is not strictly enforced beyond key validation.
  • Impact: Unauthorized content access, data scraping, potential abuse of API endpoints, depending on the API's authorization mechanisms and the sensitivity of exposed data.
  • Risk Severity: Medium to High (Severity increases if API authorization is weak beyond key validation and if sensitive data is exposed).
  • Mitigation Strategies:
    • Ghost Users/Developers:
      • Secure API Key Management: Store Ghost Content API keys securely, avoiding hardcoding them in client-side code or committing them to version control. Utilize environment variables or secure configuration management practices.
      • Regular API Key Rotation: Implement a policy for regularly rotating Ghost Content API keys to minimize the window of opportunity if a key is compromised.
      • Principle of Least Privilege for API Keys: If possible, generate API keys with the minimum necessary permissions for their intended use.
      • API Usage Monitoring: Monitor Ghost Content API usage for unusual patterns or suspicious activity that could indicate API key compromise or abuse.
      • Implement API Rate Limiting in Ghost/Infrastructure: Configure rate limiting for the Ghost Content API to mitigate abuse even if API keys are compromised.

Attack Surface: Dependency Vulnerabilities in Ghost's Node.js and npm Packages

  • Description: Ghost depends on Node.js and numerous npm packages. Security vulnerabilities in these dependencies can be exploited to compromise the Ghost application.
  • Ghost Contribution: Ghost's architecture relies on Node.js and a vast ecosystem of npm packages, inheriting the security risks associated with these dependencies.
  • Example: A critical vulnerability is discovered in a widely used npm package that Ghost depends on. Attackers exploit this vulnerability in unpatched Ghost installations to achieve remote code execution on the server.
  • Impact: Remote code execution, data breach, denial of service, depending on the severity and nature of the dependency vulnerability.
  • Risk Severity: Medium to Critical (Severity depends on the criticality of the specific dependency vulnerability).
  • Mitigation Strategies:
    • Ghost Users/Developers (System Administrators):
      • Maintain Up-to-Date Node.js and npm: Keep Node.js and npm packages used by Ghost updated to the latest stable versions, including all security patches.
      • Automated Dependency Vulnerability Scanning: Implement automated tools (e.g., npm audit, Snyk, OWASP Dependency-Check) to regularly scan Ghost's dependencies for known vulnerabilities.
      • Proactive Security Monitoring: Subscribe to security advisories and monitor vulnerability databases for notifications about vulnerabilities affecting Ghost's dependencies.
      • Establish a Patch Management Process: Develop a rapid patch management process to quickly apply security updates for Node.js and npm packages used by Ghost when vulnerabilities are identified.