SecuriFox

🇫🇷 Lire en français

SecuriFox is a screen lock for Firefox that blocks the entire browser at startup — address bar, tabs, etc. — until the profile password is entered.

Compatible: Firefox, Firefox Nightly, Firefox ESR [untested], Firefox Developer Edition [untested] Platform: Windows (PowerShell required for automatic installation) — Other OS via manual install [untested]

---

How it works

SecuriFox uses Firefox's AutoConfig mechanism to inject a privileged script (securifox-lock.uc.js) at the start of every window. This script overlays an opaque lock screen on top of the entire Firefox chrome before the user can interact with anything.

• The address bar, tabs and all Firefox menus are hidden while the lock is active
• The password is hashed with SHA-256 and stored locally in the profile preferences (prefs.js)
• No data is sent anywhere

---

Instalation

❗Attention : any new profile created after the installation will not be affected.❗

Quick install (Windows)

Close Firefox completely before running the installer.

1. Download or clone this repository

2. Open a PowerShell terminal as Administrator in the userchrome/ folder

3. Run:

   .\install.ps1

4. The script detects installed Firefox editions and asks which one to target:

   Detected installations:
     [1] Firefox          —  C:\Program Files\Mozilla Firefox
     [2] Firefox Nightly  —  C:\Program Files\Firefox Nightly
     [3] All installations
   

5. Choose the number — SecuriFox is installed on all profiles of the selected edition.

6. Open Firefox → the SecuriFox screen appears immediately. Set your password.

---

Manual install

Step 1 — AutoConfig (requires Administrator rights)

Copy these two files into your Firefox installation folder (e.g. C:\Program Files\Mozilla Firefox\):

Source	Destination
config.js	<Firefox folder>\config.js
config-prefs.js	<Firefox folder>\defaults\pref\config-prefs.js

Step 2 — Lock script (per profile)

For each profile to protect:

1. Open about:support in Firefox
2. Click "Open Folder" next to Profile Directory
3. Create a chrome/ subfolder if it doesn't exist
4. Copy securifox-lock.uc.js into that chrome/ folder
5. Restart Firefox

---

First launch

After installation, on first startup:

1. The SecuriFox screen is displayed fullscreen
2. Enter a password (minimum 4 characters) and confirm it
3. Click Create password
4. The lock is active — enter this password every time Firefox opens

Each Firefox profile has its own password. If you use multiple profiles (e.g. one per person), each person sets theirs on first launch.

---

Uninstall

Via PowerShell

# Remove AutoConfig from Firefox (adjust path if needed)
Remove-Item "C:\Program Files\Mozilla Firefox\config.js" -Force
Remove-Item "C:\Program Files\Mozilla Firefox\defaults\pref\config-prefs.js" -Force

# Remove the lock from the profile (repeat for each profile)
Remove-Item "$env:APPDATA\Mozilla\Firefox\Profiles\<profile-name>\chrome\securifox-lock.uc.js" -Force

Manually

1. Delete config.js and defaults\pref\config-prefs.js from the Firefox installation folder
2. Delete chrome\securifox-lock.uc.js from each profile folder

---

Project files

File	Role
config.js	AutoConfig loader — runs *.uc.js scripts on every Firefox window
config-prefs.js	Enables the AutoConfig mechanism in Firefox
securifox-lock.uc.js	The lock overlay (logic, UI, SHA-256 hashing)
install.ps1	Automatic installer (Windows, PowerShell)

---

Limitations & warnings

• This lock protects access via Firefox. It does not encrypt profile files on disk! Direct access to the profile folder by another program is still possible!
• To protect saved passwords in Firefox, also enable the built-in Primary Password (about:preferences#privacy → Use a Primary Password).
• For complete isolation between users, use separate Windows accounts.
• The password is stored as a SHA-256 hash in prefs.js. This is not strong encryption — do not rely on it as the sole protection for sensitive data.
• For now all interfaces are in French; as it's very straightforward, there should be no major usage issues.
• Any new profile created after the installation will not be affected. Go through the instalation process to patch it.

Tested Version

• Windows 11 - Firefox - 150.0.1 (64 bits)
• Windows 11 - Firefox Nightly - 152.0a1 (64 bits)