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attack-surface.md

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Attack Surface Analysis for symfony/finder

Attack Surface: Path Traversal Vulnerabilities

  • Description: Attackers can access files and directories outside the intended scope by manipulating file paths, potentially gaining access to sensitive data or executing arbitrary code.
  • Finder Contribution: Finder's core functionality is to operate on file paths. If user-controlled input is used to construct these paths without strict validation before being passed to Finder, the component will directly process these potentially malicious paths, enabling traversal. Finder itself doesn't inherently prevent traversal if given a malicious path.
  • Example: An application allows users to specify a directory to search. User input like ../../../../etc/passwd is directly passed to Finder->in() without validation. Finder attempts to access /etc/passwd, potentially exposing sensitive system information if the application then processes the contents.
  • Impact:
    • Unauthorized access to sensitive files (configuration files, databases, source code, system files).
    • Potential for arbitrary code execution if combined with other vulnerabilities (e.g., file upload, file inclusion).
    • Data breaches and system compromise.
  • Risk Severity: Critical to High
  • Mitigation Strategies:
    • Strict Input Validation and Sanitization Before Finder: Critically, validate and sanitize all user-provided input before it is used to construct file paths for Finder. Use whitelisting of allowed characters and patterns.
    • Path Canonicalization Before Finder: Convert paths to their canonical form before passing them to Finder to resolve symbolic links and remove redundant path separators. Compare canonical paths against allowed base directories before Finder is invoked.
    • Restricted Base Directory for Finder: Define a secure, restricted base directory. Ensure user input only specifies filenames or subdirectories within this base directory, and the base directory itself is securely defined and not user-controlled when passed to Finder->in().
    • Principle of Least Privilege: Run the application with minimal necessary permissions to limit the impact of potential path traversal, even if Finder is misused.

Attack Surface: Denial of Service (DoS) via Resource Exhaustion

  • Description: Attackers can exhaust server resources (CPU, memory, disk I/O) by triggering resource-intensive file finding operations, making the application unavailable to legitimate users.
  • Finder Contribution: Finder is designed to traverse directories and file systems based on provided patterns. Broad or maliciously crafted patterns, especially when combined with large directory structures, can directly lead to Finder consuming excessive resources during its file system operations. The more files and directories Finder needs to process, the higher the resource consumption.
  • Example: An attacker repeatedly triggers an application feature that uses Finder->in('/very/large/directory')->name('*'). Finder attempts to recursively list and process all files in /very/large/directory on each request, quickly exhausting server resources and causing a DoS.
  • Impact:
    • Application unavailability and downtime.
    • Degraded performance for legitimate users.
    • Potential server crashes.
  • Risk Severity: High
  • Mitigation Strategies:
    • Rate Limiting on Finder Operations: Implement rate limiting specifically on features that utilize Finder to prevent excessive requests that trigger resource-intensive searches.
    • Search Scope Limits within Application Logic: Within the application code that uses Finder, enforce limits on the depth and breadth of searches. Restrict the use of overly broad patterns programmatically before passing them to Finder.
    • Timeouts for Finder Operations: Set timeouts for Finder operations within the application code to prevent them from running indefinitely and consuming resources for too long. Implement this timeout around the Finder execution.
    • Resource Monitoring and Alerts: Monitor server resource usage and set up alerts to detect unusual spikes specifically related to processes using Finder or file system operations triggered by Finder.
    • Input Validation for Patterns (if user-provided): If users can provide search patterns, validate them to prevent overly broad or complex patterns that could lead to DoS. Restrict allowed pattern complexity before using them in Finder.