Mozilla Firefox Security Technical Implementation Guide

When a website asks for a certificate for user authentication, Firefox must be configured to have the user choose which certificate to present. Websites within DoD require user authentication for access, which increases security for DoD information. Access will be denied to the user if certificate management is not configured.

Updates must be controlled and installed from authorized and trusted servers. This setting overrides a number of other settings that may direct the application to access external URLs.

Set this to false to disable checking for updated versions of the Extensions/Themes. Automatic updates from untrusted sites puts the enclave at risk of attack and may override security settings.

To protect privacy and sensitive data, Firefox provides the ability to configure the program so that data entered into forms is not saved. This mitigates the risk of a website gleaning private information from prefilled information.

Firefox can be set to store passwords for sites visited by the user. These individual passwords are stored in a file and can be protected by a master password. Autofill of the password can then be enabled when the site is visited. This feature could also be used to autofill the certificate PIN, which could lead to compromise of DoD information.

Pop-up windows may be used to launch an attack within a new browser window with altered settings. This setting blocks pop-up windows created while the page is loading.

JavaScript can make changes to the browser's appearance. This activity can help disguise an attack taking place in a minimized background window. Configure the browser setting to prevent scripts on visited websites from moving and resizing browser windows.

JavaScript can raise and lower browser windows to cause improper input. Configure the browser setting to prevent scripts on visited websites from raising and lowering browser windows.

A browser extension is a program that has been installed into the browser to add functionality. Where a plug-in interacts only with a web page and usually a third-party external application (e.g., Flash, Adobe Reader), an extension interacts with the browser program itself. Extensions are not embedded in web pages and must be downloaded and installed in order to work. Extensions allow browsers to avoid restrictions that apply to web pages. For example, an extension can be written to combine data from multiple domains and present it when a certain page is accessed, which can be considered cross-site scripting. If a browser is configured to allow unrestricted use of extensions, plug-ins can be loaded and installed from malicious sources and used on the browser.

Firefox by default sends information about Firefox to Mozilla servers. There should be no background submission of technical and other information from DoD computers to Mozilla with portions posted publicly.

There should not be an option for a user to "forget" work they have done. This is required to meet non-repudiation controls.

Private browsing allows the user to browse the internet without recording their browsing history/activity. From a forensics perspective, this is unacceptable. Best practice requires that browser history is retained.

Search suggestions must be disabled as this could lead to searches being conducted that were never intended to be made.

If network prediction is enabled, requests to URLs are made without user consent. The browser should always make a direct DNS request without prefetching occurring.

The Content Blocking/Tracking Protection feature stops Firefox from loading content from malicious sites. The content might be a script or an image, for example. If a site is on one of the tracker lists that Firefox is set to use, the fingerprinting script (or other tracking script/image) will not be loaded from that site. Fingerprinting scripts collect information about browser and device configuration, such as operating system, screen resolution, and other settings. By compiling these pieces of data, fingerprinters create a unique profile that can be used to track the user around the web.

The Content Blocking/Tracking Protection feature stops Firefox from loading content from malicious sites. The content might be a script or an image, for example. If a site is on one of the tracker lists that Firefox is set to use, the fingerprinting script (or other tracking script/image) will not be loaded from that site. Cryptomining scripts use a computer's central processing unit to invisibly mine cryptocurrency.

Tracking generally refers to content, cookies, or scripts that can collect browsing data across multiple sites. It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Applications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include but are not limited to advertising software or browser plug-ins that are not related to requirements or provide a wide array of functionality not required for every mission but that cannot be disabled.

The Recommended Extensions program makes it easier for users to discover extensions that have been reviewed for security, functionality, and user experience. Allowed extensions are to be centrally managed.

A weak cipher is defined as an encryption/decryption algorithm that uses a key of insufficient length. Using an insufficient length for a key in an encryption/decryption algorithm opens up the possibility (or probability) that the encryption scheme could be broken.

The Recommended Extensions program recommends extensions to users as they surf the web. The user must not be encouraged to install extensions from the websites they visit. Allowed extensions are to be centrally managed.

The New Tab page by default shows a list of built-in top sites, as well as the top sites the user has visited. It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Applications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include but are not limited to advertising software or browser plug-ins that are not related to requirements or provide a wide array of functionality not required for every mission but that cannot be disabled. The new tab page must not actively show user activity.

DNS over HTTPS has generally not been adopted in the DoD. DNS is tightly controlled. It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Applications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include, but are not limited to, advertising software or browser plug-ins not related to requirements or providing a wide array of functionality not required for every mission, but cannot be disabled.

Disable Firefox Accounts integration (Sync). It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Applications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include but are not limited to advertising software or browser plug-ins that are not related to requirements or provide a wide array of functionality not required for every mission but that cannot be disabled.

Disable the menus for reporting sites (Submit Feedback, Report Deceptive Site). It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Applications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include but are not limited to advertising software or browser plug-ins that are not related to requirements or provide a wide array of functionality not required for every mission but that cannot be disabled.

Enable or disable Encrypted Media Extensions and optionally lock it. If "Enabled" is set to "false", Firefox does not download encrypted media extensions (such as Widevine) unless the user consents to installing them. If "Locked" is set to "true" and "Enabled" is set to "false", Firefox will not download encrypted media extensions (such as Widevine) or ask the user to install them. It is detrimental for applications to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Applications are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). Examples of non-essential capabilities include but are not limited to advertising software or browser plug-ins that are not related to requirements or provide a wide array of functionality not required for every mission but that cannot be disabled.

For diagnostic purposes, data must remain behind when the browser is closed. This is required to meet non-repudiation controls.