StrictFox

StrictFox is a hardened user.js configuration for Mozilla Firefox. It is designed to maximize privacy, security, and anti-fingerprinting while remaining practical for daily use.

This project is inspired by the research and structure of the Arkenfox project. The classic syntax-checking markers are retained as a nod to their foundational work, but the preferences are independently curated and maintained.

Prerequisites

This configuration works best as part of a layered privacy setup. For optimal protection, it should be used alongside:

1. Content Filtering: uBlock Origin for efficient, DOM-level tracker and ad blocking.
2. Secure DNS: Browser-level DNS-over-HTTPS (DoH) via Quad9 is enabled by default in this configuration.
   • Alternative: If you prefer to handle DNS at the system/Network level comment out [SECTION 0705] here user.js

Installation

1. Download the user.js file from this repository.
2. Locate your active Firefox profile directory:
   • Open Firefox and navigate to about:support.
   • Find the "Profile Folder" (or "Profile Directory") entry and click "Open Folder" (or "Show in Finder" on macOS).
3. Place the user.js file directly into this directory. If a user.js file already exists, back it up before overwriting or merge the configurations manually.
   • Optional: If you use system/network-level DNS, open the user.js file and comment out every line in [SECTION 0705]

Verification: To confirm the file loaded correctly, navigate to about:config and search for _user.js.parrot. The value should read:

SUCCESS: No no he's not dead, he's, he's restin'!

Configuration Overview

The configuration enforces the following controls:

• Telemetry Removal: Disables Mozilla telemetry, crash reporting, studies, and sponsored content.
• Anti-Fingerprinting: Enables privacy.resistFingerprinting (RFP), spoofs the locale to English, and restricts window dimensions to blend in with standard user profiles.
• Network Hardening: Disables DNS prefetching, speculative connections, and WebRTC IP leakage. Enforces HTTPS-Only mode globally. Browser-level DNS-over-HTTPS (DoH) via Quad9 is enabled by default, with a seamless fallback to system/network DNS if [SECTION 0705] is commented out.
• Disk Avoidance: Disables disk caching and forces media caching into memory to prevent local data retention.
• Shutdown Sanitization: Automatically clears history, cache, cookies, and form data on exit to prevent local data retention and session persistence.
• Attack Surface Reduction: Disables WebGL, WebGPU, asm.js, and DRM (EME).
• Baseline Security: Retains Google Safe Browsing for practical malware and phishing protection.

Operational Trade-offs

Because of these strict controls, some web features will not work out of the box. This is an intentional trade-off for privacy:

• Media Streaming: DRM-protected services (Netflix, Spotify, etc.) will not work, as EME is disabled.
• Advanced Web Apps: Sites relying on WebGL, WebGPU, or precise hardware timing may fail to render.
• Credential Management: Built-in password and form autofill are disabled. Use a dedicated password manager (e.g., Bitwarden, KeePassXC).
• RFP Quirks: privacy.resistFingerprinting may cause minor layout issues on sites that rely on dynamic window sizing or specific timezone/clipboard APIs.

Maintenance

Firefox frequently updates and changes default preferences. To maintain this security posture:

1. Periodically check this repository for user.js updates.
2. Review about:config after major Firefox updates to ensure no new tracking features have been enabled by default.

License

This project is licensed under the MIT License.