attack-surface.md

Attack Surface Analysis for hexojs/hexo

Attack Surface: Code Execution via Hexo Core Vulnerabilities

• Description: Vulnerabilities in the Hexo core application code (Node.js) that could allow an attacker to execute arbitrary code on the server during site generation.
• Hexo Contribution: Hexo's core functionality, written in Node.js, processes user-provided configuration, source files, themes, and plugins. Bugs in this processing logic can lead to code execution.
• Example: A crafted image file processed by Hexo's image handling library exploits a buffer overflow, allowing an attacker to inject and execute shell commands on the server during hexo generate.
• Impact: Full server compromise, data breach, website defacement, denial of service.
• Risk Severity: Critical
• Mitigation Strategies:
  • Keep Hexo Core Updated: Regularly update Hexo to the latest version to patch known vulnerabilities.
  • Input Validation (If extending Hexo core): If developing custom extensions to Hexo core, rigorously validate all input data.
  • Security Audits (For critical deployments): Conduct security audits of the Hexo core codebase, especially for highly sensitive deployments.

Attack Surface: Malicious Themes and Plugins

• Description: Themes and plugins from untrusted sources may contain malicious code designed to compromise the generated website or the server during the build process.
• Hexo Contribution: Hexo's architecture heavily relies on themes and plugins for customization and functionality, encouraging users to install third-party extensions.
• Example: A seemingly innocuous theme contains JavaScript code that exfiltrates user credentials from the browser when a generated page is visited, or a plugin that injects a backdoor into the generated website.
• Impact: Website compromise, client-side attacks (XSS, credential theft), server-side compromise (if plugin has server-side components), data theft.
• Risk Severity: High
• Mitigation Strategies:
  • Theme/Plugin Source Vetting: Download themes and plugins only from reputable sources (official Hexo plugin list, trusted developers).
  • Code Review: Review the code of themes and plugins before installation, especially for critical projects. Look for suspicious or obfuscated code.
  • Security Audits (For critical themes/plugins): Conduct security audits of themes and plugins, especially those handling sensitive data or core functionality.
  • Principle of Least Privilege (During build): Run the Hexo build process with limited user privileges to minimize the impact of malicious code execution during generation.

Attack Surface: Dependency Vulnerabilities in Themes and Plugins

• Description: Themes and plugins rely on external Node.js packages (dependencies). Vulnerabilities in these dependencies can be exploited indirectly through the theme or plugin.
• Hexo Contribution: Hexo's ecosystem is built on Node.js and npm, leading to a deep dependency tree for themes and plugins.
• Example: A theme uses an outdated version of a JavaScript library with a known XSS vulnerability. This vulnerability is then present in the generated website, even if the theme code itself is not directly malicious.
• Impact: Client-side attacks (XSS), potential server-side vulnerabilities depending on the dependency and its usage.
• Risk Severity: High
• Mitigation Strategies:
  • Dependency Auditing: Regularly use npm audit or yarn audit to identify and update vulnerable dependencies in package.json of themes and plugins.
  • Dependency Locking: Use package-lock.json or yarn.lock to ensure consistent dependency versions and prevent unexpected updates that might introduce vulnerabilities.
  • Automated Dependency Scanning: Integrate dependency scanning tools into the development and CI/CD pipeline to automatically detect and alert on vulnerable dependencies.

Attack Surface: Markdown Parsing Vulnerabilities

• Description: Vulnerabilities in the Markdown parser used by Hexo could be exploited by crafting malicious Markdown content, leading to unexpected behavior or code execution during site generation.
• Hexo Contribution: Hexo relies on Markdown parsers (like marked or markdown-it) to process content files. Bugs in these parsers can be exploited.
• Example: A specially crafted Markdown file with deeply nested structures or specific character combinations causes the Markdown parser to crash or consume excessive resources (DoS), or even allows for code injection if the parser is severely flawed.
• Impact: Denial of Service (DoS), potential code execution (depending on the parser vulnerability).
• Risk Severity: High
• Mitigation Strategies:
  • Keep Markdown Parser Updated: Ensure Hexo and its Markdown parser dependencies are updated to the latest versions to patch known vulnerabilities.
  • Input Sanitization (If processing external Markdown): If processing Markdown content from untrusted external sources, consider sanitizing or validating the input before processing with Hexo.
  • Choose Reputable Parsers: Hexo typically uses well-established Markdown parsers. Stick to default or widely used parsers and avoid using obscure or unmaintained ones.

Attack Surface: Path Traversal during Theme/Plugin Loading or Asset Handling

• Description: Improper handling of file paths within Hexo, themes, or plugins could allow an attacker to access or manipulate files outside the intended project directory during site generation.
• Hexo Contribution: Hexo needs to load themes, plugins, and assets from various locations. Incorrect path handling in this process can lead to path traversal.
• Example: A theme attempts to load an asset using a user-controlled path parameter without proper sanitization. An attacker could provide a path like ../../../../etc/passwd to attempt to read sensitive files on the server during hexo generate.
• Impact: Information disclosure (reading sensitive files), potential file manipulation or deletion, denial of service.
• Risk Severity: High
• Mitigation Strategies:
  • Secure File Path Handling (in themes/plugins): When developing themes or plugins, always use secure file path handling techniques. Use path joining functions provided by Node.js (path.join) and avoid directly concatenating paths with user-controlled input.
  • Input Validation and Sanitization: Validate and sanitize any user-provided input that is used to construct file paths.
  • Principle of Least Privilege (File System Access): Limit the file system access permissions of the Hexo build process to only the necessary directories.

Attack Surface: Command Injection via Hexo CLI or Configuration

• Description: If Hexo CLI commands or configuration options allow user-controlled input to be passed directly to shell commands, it could be vulnerable to command injection attacks.
• Hexo Contribution: While less common in typical Hexo usage, custom scripts, plugins, or misconfigurations could potentially introduce command injection vulnerabilities.
• Example: A plugin uses user-provided data from _config.yml to construct a shell command for an external tool without proper sanitization. An attacker could inject malicious commands into the configuration that are then executed on the server during hexo generate.
• Impact: Full server compromise, arbitrary code execution, data breach, denial of service.
• Risk Severity: Critical
• Mitigation Strategies:
  • Avoid Shell Command Execution (where possible): Minimize the use of shell commands within Hexo plugins and custom scripts. Prefer using Node.js APIs for tasks instead of shelling out.
  • Input Sanitization and Validation (for shell commands): If shell command execution is necessary, rigorously sanitize and validate all user-controlled input before passing it to shell commands. Use parameterized commands or libraries designed to prevent command injection.
  • Principle of Least Privilege (Shell Execution): Run any shell commands with the minimum necessary privileges.