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attack-surface.md

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Attack Surface Analysis for friendsofphp/goutte

Attack Surface: Cross-Site Scripting (XSS) via Parsed Content

  • Description: Vulnerability where malicious JavaScript code from a scraped website is executed in a user's browser when the application renders unsanitized content obtained by Goutte.
  • Goutte Contribution: Goutte's core function is to parse HTML and XML from external websites. This parsed content, if directly rendered by the application without sanitization, becomes a conduit for XSS attacks originating from malicious websites scraped by Goutte.
  • Example: An attacker compromises a website that the application scrapes. They inject malicious JavaScript into the website's HTML, such as: <script>alert('XSS Vulnerability!')</script>. When Goutte scrapes this page and the application displays the raw scraped HTML, the script executes in the user's browser, leading to XSS.
  • Impact: Execution of arbitrary JavaScript in a user's browser. This can result in session hijacking, cookie theft, account takeover, defacement, redirection to malicious sites, and other client-side attacks.
  • Risk Severity: High
  • Mitigation Strategies:
    • Strict Output Sanitization and Encoding: Mandatory sanitization and encoding of all HTML and XML content scraped by Goutte before rendering it in any part of the application. Use context-aware output encoding functions (e.g., HTML entity encoding, JavaScript escaping) provided by your application framework.
    • Content Security Policy (CSP): Implement a robust Content Security Policy to limit the capabilities of the browser and mitigate the impact of XSS, even if unsanitized scraped content is accidentally rendered.
    • Templating Engines with Auto-Escaping: Utilize templating engines that automatically escape output by default to minimize the risk of developers inadvertently rendering raw, unsanitized scraped content.

Attack Surface: Server-Side Request Forgery (SSRF)

  • Description: An attacker can manipulate the application to make unintended HTTP requests to internal or external resources via Goutte, potentially bypassing firewalls, accessing internal services, or leaking sensitive information.
  • Goutte Contribution: Goutte is designed to make HTTP requests to URLs provided to it. If the application allows user input or external data to influence the target URLs for Goutte scraping without proper validation, it directly enables SSRF vulnerabilities.
  • Example: An application feature allows users to "preview" a website by providing a URL. If the application uses Goutte to fetch content from this user-supplied URL without validation, an attacker could provide a URL like http://localhost/internal-admin-panel or http://169.254.169.254/latest/meta-data/ (AWS metadata endpoint) to access internal resources or sensitive cloud metadata.
  • Impact: Access to internal services and data not intended for public access, port scanning of internal networks, potential for further exploitation of internal systems, leakage of sensitive information from internal resources or cloud environments.
  • Risk Severity: High
  • Mitigation Strategies:
    • Strict URL Validation and Allowlisting: Implement rigorous validation and sanitization of all URLs used with Goutte. Use a strict allowlist of permitted domains or URL patterns. Deny any URL that does not match the allowlist.
    • Principle of Least Privilege for Scraping Processes: Run Goutte scraping operations with the minimum necessary network access and permissions. Isolate scraping processes from sensitive internal networks if possible.
    • Network Segmentation and Firewalls: Implement network segmentation to restrict the network access of the application and scraping processes. Use firewalls to prevent outbound requests to internal networks or sensitive external targets.
    • Disable Unnecessary URL Schemes: If only http and https are required, disable other URL schemes in the underlying HTTP client configuration to limit the scope of potential SSRF attacks.

Attack Surface: Injection Vulnerabilities via Untrusted Scraped Data

  • Description: Vulnerabilities like SQL Injection, Command Injection, or other injection types arise when data scraped by Goutte from external, untrusted websites is used to construct backend operations (database queries, system commands, etc.) without proper sanitization and validation.
  • Goutte Contribution: Goutte facilitates the retrieval of data from external websites, which inherently are untrusted sources. If the application treats this scraped data as safe and directly incorporates it into backend operations, Goutte becomes the mechanism by which untrusted external data enters the application's sensitive processing logic, increasing the risk of injection vulnerabilities.
  • Example: An application scrapes product names from various websites and uses these names to search a local database. If the application constructs a SQL query by directly embedding the scraped product name without sanitization: SELECT * FROM products WHERE name = ' + scrapedProductName + ', and a scraped product name contains malicious SQL code (e.g., '; DROP TABLE products; --), it leads to SQL injection.
  • Impact: Data breach, unauthorized data modification or deletion, potential for remote code execution on the server, complete compromise of the backend system and database.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Treat Scraped Data as Untrusted Input: Always consider data scraped by Goutte as untrusted input. Apply the same rigorous input validation and sanitization practices as you would for user-provided data.
    • Parameterized Queries/Prepared Statements: Exclusively use parameterized queries or prepared statements when interacting with databases to prevent SQL injection. Never construct SQL queries by concatenating scraped data directly into the query string.
    • Input Validation and Sanitization for Backend Operations: Thoroughly validate and sanitize all scraped data specifically for the context in which it will be used in backend operations. Validate data types, formats, and ranges according to expectations for each operation.
    • Principle of Least Privilege (Backend Systems): Grant minimal necessary privileges to database users and system accounts used by the application to limit the potential damage from injection vulnerabilities.
    • Avoid Dynamic Command Execution with Scraped Data: Minimize or eliminate the use of dynamic command execution based on scraped data. If absolutely necessary, implement extremely strict input validation and escaping techniques specific to the command interpreter being used.