Skip to content

Latest commit

 

History

History
69 lines (60 loc) · 6.98 KB

attack-surface.md

File metadata and controls

69 lines (60 loc) · 6.98 KB

Attack Surface Analysis for bottlepy/bottle

Attack Surface: Path Traversal via Dynamic Routes

  • Description: Attackers can manipulate URL path parameters in dynamic routes to access files or directories outside the intended application scope on the server.
  • Bottle Contribution: Bottle's dynamic routing feature allows defining routes with path parameters that can be directly used in file system operations if not handled carefully, directly enabling this attack vector.
  • Example:
    • Route definition: /static/<filepath>
    • Malicious URL: /static/../../etc/passwd
    • If the application directly uses filepath to open files without validation, an attacker can read the /etc/passwd file.
  • Impact: Information disclosure, access to sensitive system files, application source code exposure.
  • Risk Severity: High
  • Mitigation Strategies:
    • Input Validation and Sanitization: Thoroughly validate and sanitize path parameters before using them to access files. Use allowlists of allowed characters and paths.
    • Path Normalization: Use functions to normalize paths (e.g., removing .. and resolving symbolic links) to prevent traversal.
    • Restrict File Access: Limit the application's file system access to only necessary directories. Avoid using user-provided input to directly construct file paths.
    • Consider using static file serving mechanisms: If serving static files, use Bottle's built-in static file serving or a dedicated web server for better security and control.

Attack Surface: Input Validation Vulnerabilities via request Object - File Upload

  • Description: Bottle's request object provides access to user-supplied file uploads. Failure to validate and sanitize uploaded files can lead to critical vulnerabilities.
  • Bottle Contribution: Bottle's request.files attribute is the direct interface for handling file uploads, making it a key point of entry for file-based attacks.
  • Example:
    • Route handler directly saves request.files.upload.file without validation.
    • Malicious file upload: Uploading a PHP script disguised as an image.
    • If the uploaded file is accessible via the web, it could lead to remote code execution.
  • Impact: Remote Code Execution, Data Breaches, Server Compromise.
  • Risk Severity: High to Critical
  • Mitigation Strategies:
    • File Type Validation (Allowlist): Validate file types and extensions against a strict allowlist. Do not rely on client-side validation or file extension alone.
    • File Size Limits: Implement limits on file upload sizes to prevent denial of service and resource exhaustion.
    • File Name Sanitization: Sanitize file names to prevent directory traversal or other injection attacks through filenames.
    • Content Scanning: Perform virus and malware scanning on uploaded files.
    • Secure Storage: Store uploaded files outside the web root or in a dedicated storage service. Ensure proper access controls are in place.
    • Principle of Least Privilege: The application should only have the necessary permissions to handle file uploads and storage, minimizing the impact of a successful exploit.

Attack Surface: Template Injection Vulnerabilities

  • Description: If user-controlled input is directly embedded into templates without proper escaping or sanitization, attackers can inject malicious template code that executes on the server.
  • Bottle Contribution: Bottle's built-in templating and integration with other templating engines make template injection a potential risk if developers are not careful with user input within templates. Bottle facilitates template rendering, making it relevant to this attack surface.
  • Example (using a hypothetical vulnerable template engine):
    • Route handler: return template('hello_template', name=request.query.name)
    • hello_template.tpl: <h1>Hello {{ name }}</h1> (vulnerable if {{ name }} is not properly escaped and the template engine is vulnerable)
    • Malicious URL: /?name={{ system('whoami') }} (example payload for a vulnerable template engine)
    • This could execute the whoami command on the server.
  • Impact: Remote Code Execution, Information Disclosure, Server Compromise.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Always Escape User Input in Templates: Ensure that all user-provided data rendered in templates is properly escaped by the templating engine. Use auto-escaping features if available and verify they are active.
    • Use Safe Templating Engines: Choose templating engines known for their security and actively maintained.
    • Principle of Least Privilege for Template Rendering: If possible, run template rendering in a sandboxed environment with limited privileges.
    • Avoid Passing Raw User Input to Templates: Process and sanitize user input before passing it to the template engine.

Attack Surface: Input Validation Vulnerabilities via request Object - Cross-Site Scripting (XSS)

  • Description: Bottle's request object provides access to user-supplied data. Failure to sanitize user input accessed via request before rendering it in web pages can lead to Cross-Site Scripting (XSS) vulnerabilities.
  • Bottle Contribution: Bottle's request object is the primary way to access user input, and if this input is directly used in responses without sanitization, Bottle applications become vulnerable to XSS.
  • Example (XSS):
    • Route handler: return 'Hello ' + request.query.name
    • Malicious URL: /?name=<script>alert('XSS')</script>
    • The script will be executed in the user's browser when the response is rendered.
  • Impact: Client-side code execution, session hijacking, defacement, phishing attacks.
  • Risk Severity: High
  • Mitigation Strategies:
    • Output Encoding/Escaping: Encode or escape output based on the context where it's used (HTML escaping for HTML output, URL encoding for URLs, etc.). Bottle's templating engines often provide auto-escaping features, but ensure they are enabled and used correctly.
    • Content Security Policy (CSP): Implement CSP headers to mitigate XSS by controlling the sources from which the browser is allowed to load resources.
    • Input Validation (for specific cases): While output encoding is the primary defense for XSS, input validation can also play a role in certain scenarios to reject obviously malicious input.
    • Use a Templating Engine with Auto-Escaping: Leverage templating engines that automatically escape output by default to reduce the risk of developers forgetting to escape user input.