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Mitigation Strategies Analysis for librespeed/speedtest

Mitigation Strategy: Strict Rate Limiting (Speedtest-Specific)

  • Description:

    1. Identify Key Metrics: Determine appropriate rate-limiting metrics specific to speed test abuse. These should include IP address, and potentially session IDs (if user authentication is used). Geolocation is an option, but consider privacy implications.
    2. Define Limits: Establish clear limits, tailored to speed test frequency. Example:
      • IP Address: Maximum 5 tests per hour, burst allowance of 2 tests within 1 minute.
      • Session ID: Maximum 10 tests per session.
    3. Implement Rate Limiting Logic: Use a suitable mechanism (Redis, database, middleware) to track and enforce. Prioritize server-side enforcement.
    4. Graceful Degradation: Instead of hard blocking, use HTTP 429 (Too Many Requests), Retry-After header, informative messages, and potentially reduce test size/duration for subsequent attempts.
    5. Dynamic Adjustment (Optional): Monitor server load (CPU, network) and adjust rate limits programmatically.

  • Threats Mitigated:

    • Denial of Service (DoS) (Severity: High): Prevents overwhelming the server with speed test requests.
    • Resource Exhaustion (Severity: High): Limits CPU, memory, and bandwidth consumption specific to speed test operations.
    • Abuse of Functionality (Bandwidth Costs) (Severity: Medium): Reduces excessive bandwidth usage from speed tests.

  • Impact:

    • DoS: Significantly reduces successful DoS attack risk.
    • Resource Exhaustion: Greatly reduces server overload from excessive speed tests.
    • Abuse of Functionality: Moderately reduces excessive bandwidth consumption.

  • Currently Implemented:

    • Partially. The librespeed backend (PHP example) lacks built-in rate limiting. Example HTML files suggest Cloudflare (external), but it's not inherent. IP logging (a prerequisite) is mentioned, but not rate limiting itself.

  • Missing Implementation:

    • Backend Logic: The core librespeed backend (e.g., example-php/backend/empty.php) needs explicit rate-limiting logic. This is the critical missing piece.
    • Configuration Options: The project could benefit from configuration options for easy rate limiting customization.

Mitigation Strategy: Test Duration and Size Limits

  • Description:

    1. Review Existing Parameters: Examine librespeed's parameters (e.g., xhr_dl_blob_size, xhr_ul_blob_size, time_ul_max, time_dl_max) in the example HTML files.
    2. Set Reasonable Maximums: Based on server capacity and expected usage, set strict maximums for these parameters. Be conservative. Example:
      • time_ul_max: 15 seconds.
      • time_dl_max: 15 seconds.
      • xhr_dl_blob_size and xhr_ul_blob_size: Calculate based on target bandwidth and duration.
    3. Enforce Limits Server-Side: Crucially, enforce limits on the server (e.g., PHP backend), not just client-side. The server should:
      • Validate requested parameters against maximums.
      • Terminate tests exceeding time limits.
      • Reject requests for excessively large data.
    4. Consider Tiered Testing (Optional): Offer different test sizes/durations based on authentication (e.g., shorter tests for unauthenticated users).

  • Threats Mitigated:

    • Denial of Service (DoS) (Severity: High): Prevents long/large tests from consuming excessive resources.
    • Resource Exhaustion (Severity: High): Limits resource consumption per test.
    • Abuse of Functionality (Bandwidth Costs) (Severity: Medium): Reduces bandwidth usage by limiting test size/duration.

  • Impact:

    • DoS: Significantly reduces DoS risk from long/large tests.
    • Resource Exhaustion: Greatly reduces overload from individual tests.
    • Abuse of Functionality: Moderately reduces excessive bandwidth.

  • Currently Implemented:

    • Partially. Example HTML files have configurable parameters. However, server-side enforcement is weak or missing.

  • Missing Implementation:

    • Server-Side Enforcement: The backend (e.g., example-php/backend/empty.php) must actively validate parameters and terminate tests exceeding limits. This is the critical missing piece. The current backend focuses on data transfer, not strong limit enforcement.
    • Clear Error Handling: Return informative errors if limits are exceeded.

Mitigation Strategy: Client IP Address Handling (Privacy-Focused, Speedtest Context)

  • Description:

    1. Assess Necessity: Determine if logging client IPs is essential for your speed test's purpose. Consider privacy laws (GDPR).
    2. Disable Logging (If Possible): If not required, disable it in the librespeed backend. The PHP example has $enable_logging; set it to false.
    3. If Logging is Required:
      • Minimize Retention: Store IPs for the shortest time needed (abuse detection, troubleshooting).
      • Anonymization/Pseudonymization: After retention, anonymize (irreversibly remove) or pseudonymize (replace with an unlinkable ID).
      • Access Control: Strict access to IP logs; authorized personnel only.
      • Encryption: Consider encrypting logs at rest.
      • Transparency: Clearly state in your privacy policy how IPs are handled.

  • Threats Mitigated:

    • Information Disclosure (Privacy) (Severity: Medium): Reduces exposure of user IPs (PII).
    • Compliance Violations (Severity: High, jurisdiction-dependent): Helps with GDPR, CCPA, etc.

  • Impact:

    • Information Disclosure: Significantly reduces privacy risks related to IP collection.
    • Compliance Violations: Reduces legal/financial penalties for non-compliance.

  • Currently Implemented:

    • Partially. The PHP backend example has $enable_logging to disable logging. However, it lacks anonymization, pseudonymization, or automated retention.

  • Missing Implementation:

    • Anonymization/Pseudonymization: The backend needs built-in mechanisms for these.
    • Data Retention Policy: The project lacks tools/guidance for IP log retention.
    • Documentation: The documentation should emphasize privacy implications and best practices.