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This guide shows a user in an easy-to-follow way how to improve the privacy and security settings of Firefox, which, when combined with a privacy VPN, gives a user a strong framework for protecting their browsing habits.

 
Firefox Addons

 

HTTPS Everywhere: HTTPS everywhere makes sure that all of the requests coming from your browser request SSL encryption, so that if it is available, it is used by default.

LastPass: As per our guide on passwords, we recommend utilising a password manager such as lastPass or Mooltipass.

Lightbeam: You can check the impact of your changes using Lightbeam. Lightbeam monitors the requests that are made when you are visiting a website and gives you a visual layout so that you can see where your data is going. 

Privacy Badger: Extensions like Disconnect and others block cookies by comparing the cookies to known ones. The EFF’s Privacy Badger blocks cookies by tracking their behavior rather than comparing them to repositories. This allows Privacy Badger to actively block new threats as they appear, even with no frame of reference to work from.

uBlock Origin: Not to be confused with uBlock, uBlock Origin is a powerful ad-blocking tool that prevents most types of ads from appearing in your browsing or streaming. uBlock Origin does not have a whitelist and universally blocks all of the ads that it can. It is crucial to block ads because it is a common vector for both surveillance and malware.

uMatrix: uMatrix is a powerful and script, cookie, and cross-site request blocker. It can recognize and block tracking through media and image files, and gives you granular control over what you allow and what you disallow on a per-site basis.

 

Firefox Settings

General

The built in Firefox spell checker operates using local language libraries that are built into the browser. This means that your keystrokes and what you write are not uploaded to Mozilla or any 3rd party by the spellchecker. Please Note: Websites can disable the built-in spell checker and use their own, like gmail. This means when you are on websites you should be aware that your keystrokes within that page can always be recorded by the site and/or any 3rd party scripts running on that site.

Home

Having a homepage that is not a blank page allows the site in question to know every time you’ve opened Firefox or started a new tab.

Search

DuckDuckGo is a private search engine that does not store or cache user results. This means that your searches remain private and are not sold for marketing or surveillance purposes. Because of the non-invasive approach of DuckDuckGo, some focused searches may not give you the most relevant results. To fix this, you can use a feature called Bangs to have DuckDuckGo redirect your search to another engine like Wikipedia or Startpage in a private way. For Startpage you do this by preceding your search in the navigation bar with a !sp.

!sp (search term)

Search Suggestions is a feature that tries to predict what you’re typing in the search bar and provide you with relevant results before you finish typing out your search. It does this by analyzing your keystrokes in real-time through an interactive service. This means that the search provider is getting all of your information on keystrokes that type into the bar as soon as you hit the spacebar, not when you complete typing your search. This isn’t a huge privacy concern unless you leave a non-private search engine as your default.

Privacy and Security

Do not save Passwords or allow autofill

Do not store History.

Do not allow 3rd party cookies as these are nearly exclusively used for tracking.

You should leave first party cookies enabled because this gives you the option of allowing a cookie for a specific site with the uMatrix plugin. This corrects a lot of site-breaking issues for sites that you frequently visit in which specific cookies are okay.

Do not allow any suggestions in the search bar, as these broadcast your activity to 3rd parties.

Tracking protection can be enabled, but it is handled by addons as well, so it is redundant.

Block popups because not only are they annoying, but also because they are a common method of delivering malware payloads through malicious pages.

You want Firefox to warn you when sites try to install addons, as these have all kinds of security and privacy consequences.

Accessibility services are typically used in surveillance plugins for corporate networks and privacy unfriendly addons for Firefox, they should be disabled.

Do not share telemetry data with Mozilla.

Blocking Dangerous and Deceptive Content: Firefox utilises the Update API. This stores a list of unsafe sites and domains locally, and you download a list from Google periodically that updates this list of domains. This method does not give Google any information from the user and it is what Firefox uses. You do not need to disable this feature for privacy reasons and it does generally boost your security by checking your browsing against the blacklisted sites.

Trusted Root CAs

Certificates around the web tell your browser if a site is genuine and they are managed by a group of “root certificates” from organizations around the world. These organizations vouch for the security of their own root certificate and vouch for the validity of all certificates that are made from it. This means that when a site creates a certificate for a website, they are telling your browser “this site is genuine because the certificate says it is.” You are relying on the reputation of the certificate issuer to keep your browser safe from spoofing.

There’s some inherent problems with this system. How do we know that the issuer's security standards are perfect? How do we know that the issuer's would never create an invalid certificate for someone else accidentally? How do we know that the issuer's would never create a fake certificate for a law enforcement agency or spy organization?

Therein lies a large problem. Firefox (and all browsers and operating systems) trust hundreds of these root certificates by default, and for most users around the world, you don’t encounter most of these root certificates in your day to day web use.

For an example of certificate authorities that people may not want to blindly trust:

As a privacy and security, we suggest to not blindly trust certificates originating from China (or other restrictive countries) due to their history of monitoring.

You can remove many of these root certificates from Firefox to make it so that you trust far fewer authorities. To access the certificate manager, you go to the settings menu in Firefox, and click on the Privacy and Security pane on the left side. Then you scroll to the bottom of the page and click on “View Certificates…” In the window that opens up, you can scroll through all of the possible certificate authorities and remove trust (by clicking on the Delete or Distrust… button) from all of the authorities for sites that you do not visit or do not trust for ethical reasons.

This step does require some research, you have to find out which certificates are used by the sites you visit, and limit your trusted certificates to those. Also, many of the big American certificate authorities (such as the Amazon Root CAs, DigiTrust, RapidSSL, GeoTrust, GlobalSign) will break a majority of your websites visited if you mistrust them.

Sync

Synchronizing your account across multiple devices has multiple privacy and security risks that should be avoided. Do not sign in to a Firefox account.

 

Firefox Advanced Settings

Firefox is highly configurable for privacy, and to access hundreds of advanced settings, you type about:config into the navigation bar. You will see a warning telling you to be careful! It is a warning worth heeding as setting things up incorrectly can make your browser crash or cause all kinds of issues. Misconfiguration can require a full reset of browser settings that will make you have to start over the process of hardening your browser.

The changes below are designed to significantly reduce the number of methods that websites can profile your activity. Why each setting is selected to be changed is included in the description of the setting.

Disable WebRTC
WebRTC is a protocol related to digital rights management that helps content websites track users. It has the capability to give up your real IP address even while connected to a VPN or Tor.

To disable WebRTC: Type media.peerconnection.enabled and double click on the setting to change it to false.

 

Enable Fingerprint Resistance
This setting actually manages many behaviors in Firefox, it is a group of settings that are used by the Uplift project (a sub-project of Tor) to make the browser ignore most types of fingerprinting requests.

To enable Fingerprint Resistance: Type privacy.resistfingerprinting into the search bar and double click on the setting to set it to “true.”

Disable the 3DES cipher
This setting allows the 3DES cipher, which has multiple known security weaknesses. It needs to be disabled.

To disable 3DES: Type security.ssl3.rsa_des_ede3_sha into the search bar, and double click on the setting to set it to “false.” This prevent 3des from being supported.

Require Safe Negotiation
This setting is for preventing a code injection attack related to how clients and servers negotiate which encryption settings to use. This setting forces only safe negotiation methods to be used.

To enable Require safe negotiation: Type security.ssl.require_safe_negotiation into the search bar, and double click the setting to set it to “true.” This prevents this code injection attack from working.

Disable TLS versions 1.0 and 1.1
Transport Layer Security (TLS) is a protocol created by industry consensus for creating secure connections between web resources and applications. The current standard version of TLS is 1.2 and version 1.3 is rapidly being adopted at the time of this writing. TLS version 1.0 and 1.1 (1.0 esecially) have some known flaws with negotiation and cryptography in certain situations, and should be disabled for security reasons.

To Disable TLS 1.0 and TLS 1.1: Type security.tls.version.min into the search bar, and double click on the setting. In the box that pops up, type 3 and hit okay. This will force Firefox to only use TLS 1.2 and TLS 1.3.

Disable 0-RTT
Zero Round Trip Time Resumption (0-RTT) is a feature that is new in TLS 1.3 that allows a client and server to negotiate a connection with fewer steps, allowing https websites to load more quickly. There are two problems with this. First, in order to do this you lose forward secrecy (generating a new key for every session and throwing away the key when the session is over). Secondly, 0-RTT requires special implementation in order to prevent replay attacks, which some web developers will certainly fail to protect from. Disabling 0-RTT enhances security and privacy.

To Disable 0-RTT: Type security.tls.enable_0rtt_data into the search bar, and double click on the setting to set the feature to false. This will force full secure negotiation for all connections made by Firefox.

Disable Automatic Formfill
Formfilling requires that information be cached in the browser, this can include valuable information like usernames and passwords and the information can reference visited sites even with history disabled.

To Disable Formfill: Type browser.formfill.enable into the search bar, and double click on the setting to set the feature to false. This will prevent Formfill from caching any information about your browsing.

Disable All Disk Caching
Websites can write temporary information to hard drives such as access tokens, security keys, browsing data, secure scripts, and more. This information is usually deleted after a secure session is terminated, however, deleted information is trivially recoverable if it is not overwritten. Complicated firmware and drivers for flash memory based devices like SSDs introduce features like wear leveling that hide components of the storage from the OS entirely, making it very hard to verify that deleted information is actually deleted in an unrecoverable way.

To Disable all Disk Caching: Type browser.cache into the search bar. This will pull up many settings. Look for these specific settings and set them all to false::

• browser.cache.disk.enable
• browser.cache.disk_cache_ssl
• browser.cache.memory.enable
• browser.cache.offline.enable
• browser.cache.insecure.enable

This will disable all types of disk caching in Firefox.

Disable Geolocation Services
Geolocation services are bad for privacy for obvious reasons. You don’t want people lasering on your exact location.

To Disable Geolocation: Type geo.enabled into the search bar, and double click the setting to set it to false. This will prevent geolocation services from working. (Note: WebRTC should also be disabled as mentioned above, as it uses a different method of generating location data.)

Disable Plugin Scanning
Plugins can query what extensions and plugins that you have installed on Firefox to profile users. Disabling this feature improves both privacy and functionality while browsing privately.

To Disable Plugin Scanning: Search for plugin.scan.plid.all and double click the setting to set it to false. This will disable the feature.

 

Disable ALL Telemetry Features
These are features that explicitly collect data.

To Disable All Telemetry: Type telemetry into the search bar. A large number of settings will pop up in the search. Search for the following and set them all to false:

• browser.newtabpage.activity-stream.feeds.telemetry
• browser.newtabpage.activity-stream.telemetry
• browser.pingcentre.telemetry
• devtools.onboarding.telemetry-logged
• media.wmf.deblacklisting-for-telemetry-in-gpu-process
• toolkit.telemetry.archive.enabled
• toolkit.telemetry.bhrping.enabled
• toolkit.telemetry.firstshutdownping.enabled
• toolkit.telemetry.hybridcontent.enabled
• toolkit.telemetry.newprofileping.enabled
• toolkit.telemetry.unified
• toolkit.telemetry.updateping.enabled
• toolkit.telemetry.shutdownpingsender.enabled

These changes prevent all kinds of metadata from being stored about your connection both locally and by Mozilla.

Disable Prefetching
Firefox by default will pre-load all linked pages on pages that you visit. This becomes a privacy issue because this leads to your browser broadcasting a list of the links that are on the page you are currently visiting, which can allow outside parties to profile your browsing habits from your DNS traffic, or, if you’re not on a VPN it can allow your ISP to infer what web pages you visit within secure sites by looking at the prefetch resources.

To Disable DNS Prefetching: Type network.dns.disableprefetch into the search bar and double click on the option to set the option to True. This will prevent the browser from broadcasting your browsing habits through DNS requests.

To Disable Network Prefetching: Type network.prefetch-next into the search bar and double click the option to set it to false.

Disable Referral Headers
Websites use referral headers to track users movements from one site to another. This tells the website you are visiting what site that you came from.

To Disable HTTP Referral Headers: Type network.http.sendRefererHeader into the search bar and double click the setting which will open a dialog box. Type 0 into the box that pops up and hit okay to completely disable Referral headers.

Disable WebGL
WebGL is an application interface that allows websites direct access to your graphics card. This introduces a huge attack surface for potential security risks as well as unique types of fingerprinting. It should be disabled.

To Disable WebGL: Type webgl.disabled into the search bar, and double click on the option that is displayed to set it to true.

Disable Battery API
The Mozilla API can allow a site to track the current battery life of a device, which can be used in conjunction with other methods to identify and track users.

To Disable the Battery API: Type dom.battery.enabled into the search bar and double click the option listed to set it to false.

Disable Session Identifiers
Disable session identifiers: Type security.ssl.disable_session_identifiers ensure Boolean is selected and click the large + on the right and ensure that it is set to TRUE.

Enable First-Party Isolation
This feature prevents the browser from making requests to sites outside of the primary domain from the site. This prevents large ubiquitous services from following your keys around the web like a supercookie, and it also prevents all kinds of 3rd party data tracking.

To enable first party isolation: Type privacy.firstparty.isolate ensure Boolean is selected and click the large + on the right and ensure that it is set to TRUE. Please Note: This setting can break websites that rely heavily on 3rd party libraries and scripts.

Disable TLS False Start
This is because it does not allow the client to fully complete its handshake before starting the actual session.

To disable TLS false start: Type security.ssl.enable_false_start ensure Boolean is selected and click the large + on the right and ensure that it is set to FALSE.

About Camera and Microphone Access – There are many settings in Firefox related to access to the Camera and Microphone. Recently, Firefox has implemented a number of good security and privacy features surrounding access that make editing these settings unnecessary. Disabling these features in about:config will disable Mic and Camera access globally, rather than allow you to permit access to services that you desire.

If you NEVER want to use a microphone or webcam through your browser, you can manually disable access. Otherwise, you should allow your permissions built into Firefox to manage access.