github-attack-surface-flask-deepseekdeepseek-r1.md

February 8, 2025 · View on GitHub

Critical/High Risk Flask-Specific Attack Surfaces

1. Insecure Route Handlers with Raw Input Usage

  • Description: Endpoints directly using unsanitized user input from Flask's request objects.
  • Flask Contribution: request.args, request.form, and request.json expose raw user input.
  • Example: user_input = request.args.get('param') used in SQL queries without parameterization.
  • Impact: SQL injection, command injection, or server compromise.
  • Severity: Critical
  • Mitigation: Use Flask-SQLAlchemy for parameterized queries, validate inputs with Flask-WTF, and sanitize with bleach.

2. Jinja2 Server-Side Template Injection (SSTI)

  • Description: Dynamic template rendering with user-controlled content.
  • Flask Contribution: render_template_string() allows unsafe template rendering.
  • Example: render_template_string(f"Welcome {user_input}") where user_input = {{ config.SECRET_KEY }}.
  • Impact: Secret leakage, remote code execution.
  • Severity: Critical
  • Mitigation: Avoid render_template_string, enforce strict variable escaping, and sandbox Jinja2 environments.

3. Weak Client-Side Session Management

  • Description: Predictable or tamperable session cookies.
  • Flask Contribution: Flask stores sessions in signed (but not encrypted) client-side cookies by default.
  • Example: Using a weak SECRET_KEY (e.g., 'dev') or missing SESSION_COOKIE_SECURE.
  • Impact: Session hijacking, privilege escalation.
  • Severity: High
  • Mitigation: Set a strong SECRET_KEY, enable SESSION_COOKIE_SECURE, SESSION_COOKIE_HTTPONLY, and consider server-side sessions with Flask-Session.

4. Authentication Bypass via Flawed Decorators

  • Description: Custom route decorators with insufficient authorization checks.
  • Flask Contribution: Flask’s decorator-based routing enables custom auth logic.
  • Example: A decorator that checks if user.is_authenticated but skips role validation.
  • Impact: Unauthorized access to admin endpoints.
  • Severity: High
  • Mitigation: Use Flask-Login for auth workflows and enforce RBAC with Flask-Principal.

5. Insecure File Uploads via request.files

  • Description: Unsafe handling of uploaded files leading to path traversal or malware execution.
  • Flask Contribution: request.files provides direct access to file streams.
  • Example: Saving files using filename = request.files['file'].filename without sanitization.
  • Impact: Remote code execution, directory traversal.
  • Severity: Critical
  • Mitigation: Use werkzeug.utils.secure_filename, restrict file extensions, and store files outside the web root.

6. Unsafe Deserialization with pickle

  • Description: Deserializing untrusted data from Flask requests.
  • Flask Contribution: Developers might use pickle for session/cache data.
  • Example: user_data = pickle.loads(request.cookies.get('user')).
  • Impact: Remote code execution.
  • Severity: Critical
  • Mitigation: Replace pickle with JSON serialization and validate data schemas.

7. Blueprint/Extension Exploitation

  • Description: Vulnerabilities in third-party Flask extensions or misconfigured blueprints.
  • Flask Contribution: Extensions like Flask-Admin or Flask-RESTful often integrate deeply with the app.
  • Example: Exposed Flask-Admin panel without authentication at /admin.
  • Impact: Full application compromise via admin interfaces.
  • Severity: Critical
  • Mitigation: Audit extensions, disable unused components, and enforce strict access controls.