The Firefox New Tab page must not show top sites.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-251573	FFOX-00-000029	SV-251573r807191_rule		Medium

Description
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.

Description

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.

STIG	Date
Mozilla Firefox Security Technical Implementation Guide	2021-12-01

Details

Check Text ( C-55008r807189_chk )
Type "about:policies" in the browser address bar. If "FirefoxHome" is not displayed under Policy Name or the Policy Value does not have "TopSites" with a value of "false", this is a finding.

Fix Text (F-54962r807190_fix)
Windows group policy: 1. Open the group policy editor tool with "gpedit.msc". 2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Mozilla\Firefox Policy Name: Customize Firefox Home Policy State: Enabled Policy Value: Uncheck Top Sites macOS "plist" file: Add the following: FirefoxHome TopSites Linux "policies.json" file: Add the following in the policies section: "FirefoxHome": { "TopSites": false }

Fix Text (F-54962r807190_fix)

Windows group policy:
1. Open the group policy editor tool with "gpedit.msc".
2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Mozilla\Firefox
Policy Name: Customize Firefox Home
Policy State: Enabled
Policy Value: Uncheck Top Sites

macOS "plist" file:
Add the following:
FirefoxHome

TopSites

Linux "policies.json" file:
Add the following in the policies section:
"FirefoxHome": {
"TopSites": false
}