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attack-surface.md

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Attack Surface Analysis for bcosca/fatfree

Attack Surface: Server-Side Template Injection (SSTI)

  • Description: Exploiting vulnerabilities in the template engine to inject malicious code that executes on the server.
  • How Fat-Free Contributes: F3's built-in template engine, using tags like {{ @variable }} and {{ function() }}, directly processes template code. If user-controlled input is incorporated into templates without proper sanitization, F3's template engine becomes the execution vector for injected code.
  • Example:
    • Vulnerable Code: $f3->set('template', 'Hello {{ $_GET["name"] }}'); echo Template::instance()->render('template');
    • Attack Payload: ?name={{ system('whoami') }}
    • Explanation: The attacker injects {{ system('whoami') }} as the name parameter. F3's template engine interprets and executes this injected code, running the whoami command on the server.
  • Impact: Critical. Full server compromise, arbitrary code execution, data breaches, denial of service.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Parameterize Template Variables: Treat user input as data, not code. Avoid dynamically constructing template strings with user input.
    • Output Encoding/Escaping: Utilize F3's template engine's escaping mechanisms to automatically encode output based on context, preventing interpretation of injected code.
    • Input Validation and Sanitization: Validate and sanitize user input before using it in templates as a defense-in-depth measure, even with output escaping.

Attack Surface: SQL Injection Vulnerabilities

  • Description: Exploiting vulnerabilities in database queries to inject malicious SQL code, allowing unauthorized data access, modification, or deletion.
  • How Fat-Free Contributes: While F3 provides database abstraction and encourages parameterized queries through its DB\SQL and DB\Cortex classes, developers can bypass these secure methods and directly use $db->exec() with raw SQL. Improperly constructed queries using string concatenation with user input directly leverage F3's database interaction capabilities for malicious purposes.
  • Example:
    • Vulnerable Code: $username = $_GET['username']; $sql = "SELECT * FROM users WHERE username = '$username'"; $result = $f3->get('DB')->exec($sql);
    • Attack Payload: ?username='; DELETE FROM users; --
    • Explanation: The attacker injects SQL code that is directly passed to the database engine via F3's $db->exec() method, leading to unintended database operations.
  • Impact: Critical. Data breaches, data loss, data manipulation, unauthorized access to sensitive information, denial of service.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Parameterized Queries (Prepared Statements): Always use parameterized queries or prepared statements offered by F3's database classes. This prevents user input from being interpreted as SQL code.
    • ORM/Database Abstraction: Utilize F3's ORM features (DB\Cortex) to further abstract database interactions and minimize raw SQL usage.
    • Input Validation and Sanitization: Validate and sanitize user input before using it in database queries, even when using parameterized queries, as a secondary security layer.

Attack Surface: File Inclusion Vulnerabilities

  • Description: Exploiting vulnerabilities to include arbitrary files, potentially leading to code execution or sensitive data disclosure.
  • How Fat-Free Contributes: If developers use F3's routing or view rendering mechanisms to dynamically determine file paths based on user input and then use PHP's include() or require() functions, it can lead to file inclusion. F3's flexibility in handling views and routing can be misused if path construction is not carefully managed.
  • Example:
    • Vulnerable Code: $page = $_GET['page']; include('views/' . $page . '.php');
    • Attack Payload (LFI): ?page=../../../../etc/passwd
    • Explanation: The attacker manipulates the page parameter, which is directly used in a file path within an include() statement. F3's routing or controller logic might facilitate passing this user input to the vulnerable include() call.
  • Impact: High to Critical. Sensitive data disclosure (LFI), remote code execution (RFI if allow_url_include is enabled, though discouraged).
  • Risk Severity: High (can be Critical with RFI or execution of included files)
  • Mitigation Strategies:
    • Avoid Dynamic File Paths: Do not construct file paths based on user input. Use a whitelist of allowed files or predefined paths for views and includes.
    • Input Validation: Strictly validate user input if dynamic file paths are unavoidable. Sanitize input to prevent path traversal attempts.
    • Restrict File Access Permissions: Configure file system permissions to limit access to sensitive files and directories by the web server process.

Attack Surface: Configuration Exposure and Misconfiguration (Debug Mode)

  • Description: Exposing sensitive information through misconfiguration, specifically by leaving debug mode enabled in production.
  • How Fat-Free Contributes: F3's DEBUG configuration setting controls the level of error reporting and debugging information displayed. Setting DEBUG to 3 in production environments, as facilitated by F3's configuration system, exposes detailed error messages, internal paths, and potentially sensitive variables to users.
  • Example:
    • Misconfiguration: DEBUG=3 is set in the F3 configuration file in a production environment.
    • Attack Scenario: An application error occurs. F3 displays a detailed error page to the user, revealing server paths, code snippets, and potentially database connection details or other sensitive information.
  • Impact: High. Sensitive information disclosure (internal paths, code structure, potentially credentials in error messages), aiding attackers in further exploitation.
  • Risk Severity: High
  • Mitigation Strategies:
    • Disable Debug Mode in Production: Ensure DEBUG is set to 0 in production environments. Use different configuration settings for development and production.
    • Secure Configuration Files: Protect F3 configuration files from public access using web server configurations and file system permissions.

Attack Surface: Session Management Vulnerabilities (Configuration & Implementation)

  • Description: Weaknesses in session handling that can lead to session hijacking or fixation, potentially allowing account takeover.
  • How Fat-Free Contributes: F3 provides session management through the \Session class. While F3 offers session functionality, developers are responsible for secure configuration and implementation. Default session configurations or neglecting to implement session fixation protection within an F3 application can create vulnerabilities.
  • Example:
    • Vulnerability: Application fails to regenerate session IDs after user login (session fixation).
    • Attack Scenario: An attacker tricks a user into using a known session ID. After the user logs in, the attacker reuses the same session ID to gain access to the user's account.
  • Impact: High. Account takeover, unauthorized access to user data and functionality, privilege escalation.
  • Risk Severity: High
  • Mitigation Strategies:
    • Session Fixation Protection: Implement session ID regeneration after user authentication within the F3 application logic.
    • Secure Session Configuration: Configure F3's session handling to use strong session IDs and secure session storage mechanisms.
    • HTTPS: Enforce HTTPS to protect session cookies from network sniffing.
    • session.cookie_httponly and session.cookie_secure (PHP Configuration): Ensure these PHP directives are enabled for enhanced session cookie security, which F3 applications rely on.