Blocked websites (Mozilla Firefox Group Policy)

What it does

If this policy is enabled, you can specify match patterns that indicate sites to be blocked. The match patterns are documented at https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Match_patterns. There is a 1000 entry limit. If this policy is disabled or not configured, no websites are blocked.

What it writes

Hive: HKEY_LOCAL_MACHINE or HKEY_CURRENT_USER
Registry key: Software\Policies\Mozilla\WebsiteFilter\Block

Options

Option	Type	Registry value	Allowed values
Website Filter (JSON)	List of values	`Software\Policies\Mozilla\Firefox\WebsiteFilter\Block`	Any

Configure and deploy

Choose a state and the option values; the output below is generated from the template for exactly that.

Enabled · Computer · template defaults

Registry file (.reg)

Windows Registry Editor Version 5.00

[-HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox\WebsiteFilter\Block]

PowerShell

$ErrorActionPreference = 'Stop'

function Set-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name,
        [Parameter(Mandatory = $true)][string] $PropertyType,
        [Parameter(Mandatory = $true)][object] $Value
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        New-Item -Path $Path -Force | Out-Null
    }

    New-ItemProperty -LiteralPath $Path -Name $Name -PropertyType $PropertyType -Value $Value -Force | Out-Null
}

function Remove-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name
    )

    if (Test-Path -LiteralPath $Path) {
        Remove-ItemProperty -LiteralPath $Path -Name $Name -Force -ErrorAction SilentlyContinue
    }
}

function Clear-RegistryKeyValues {
    param(
        [Parameter(Mandatory = $true)][string] $Path
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return
    }

    foreach ($propertyName in (Get-Item -LiteralPath $Path).Property) {
        Remove-ItemProperty -LiteralPath $Path -Name $propertyName -Force -ErrorAction SilentlyContinue
    }
}

# Policy: Blocked websites
# Name: B_WebsiteFilter_Block
# Scope: Machine
# State: Enabled
# Source: firefox.admx

Clear-RegistryKeyValues -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox\WebsiteFilter\Block'

The OMA-URI is an inferred ADMX-backed Policy CSP candidate derived from the source ADMX file name and policy name.
Some Microsoft policies use built-in Policy CSP pages whose area names don't match the ADMX file name, so verify the candidate against Microsoft Learn before deployment.
The generated payload is incomplete because one or more ADMX element values were not supplied: WebsiteFilter

ADMX profile candidate (OMA-URI)

./Device/Vendor/MSFT/Policy/Config/ADMX_firefox/B_WebsiteFilter_Block

Intune remediation scripts

Detection

$ErrorActionPreference = 'Stop'
$reasons = [System.Collections.Generic.List[string]]::new()

function Test-RegistryValueExists {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return $false
    }

    return $null -ne (Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction SilentlyContinue)
}

function Test-RegistryValueEquals {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name,
        [Parameter(Mandatory = $true)][string] $Kind,
        [Parameter(Mandatory = $true)][object] $Expected
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return $false
    }

    $valueObject = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction SilentlyContinue
    if ($null -eq $valueObject) {
        return $false
    }

    $actual = $valueObject.$Name
    switch ($Kind) {
        'String' { return [string]$actual -ceq [string]$Expected }
        'ExpandString' { return [string]$actual -ceq [string]$Expected }
        'DWord' { return [uint32]$actual -eq [uint32]$Expected }
        'QWord' { return [uint64]$actual -eq [uint64]$Expected }
        'MultiString' {
            $actualArray = @($actual)
            $expectedArray = @($Expected)
            if ($actualArray.Count -ne $expectedArray.Count) { return $false }
            for ($index = 0; $index -lt $actualArray.Count; $index++) {
                if ([string]$actualArray[$index] -cne [string]$expectedArray[$index]) { return $false }
            }
            return $true
        }
        'Binary' {
            $actualArray = [byte[]]$actual
            $expectedArray = [byte[]]$Expected
            if ($actualArray.Length -ne $expectedArray.Length) { return $false }
            for ($index = 0; $index -lt $actualArray.Length; $index++) {
                if ($actualArray[$index] -ne $expectedArray[$index]) { return $false }
            }
            return $true
        }
        default { return [string]$actual -ceq [string]$Expected }
    }
}

# Policy: Blocked websites
# Name: B_WebsiteFilter_Block
# Scope: Machine
# State: Enabled
# Source: firefox.admx

$keyPath = 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox\WebsiteFilter\Block'
if (Test-Path -LiteralPath $keyPath) {
    $propertyNames = (Get-Item -LiteralPath $keyPath).Property
    if ($propertyNames.Count -gt 0) {
        $reasons.Add('Key should be empty: HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox\WebsiteFilter\Block') | Out-Null
    }
}

if ($reasons.Count -eq 0) {
    Write-Output 'Compliant'
    exit 0
}

$reasons | ForEach-Object { Write-Output $_ }
exit 1

Remediation

$ErrorActionPreference = 'Stop'

function Set-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name,
        [Parameter(Mandatory = $true)][string] $PropertyType,
        [Parameter(Mandatory = $true)][object] $Value
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        New-Item -Path $Path -Force | Out-Null
    }

    New-ItemProperty -LiteralPath $Path -Name $Name -PropertyType $PropertyType -Value $Value -Force | Out-Null
}

function Remove-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name
    )

    if (Test-Path -LiteralPath $Path) {
        Remove-ItemProperty -LiteralPath $Path -Name $Name -Force -ErrorAction SilentlyContinue
    }
}

function Clear-RegistryKeyValues {
    param(
        [Parameter(Mandatory = $true)][string] $Path
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return
    }

    foreach ($propertyName in (Get-Item -LiteralPath $Path).Property) {
        Remove-ItemProperty -LiteralPath $Path -Name $propertyName -Force -ErrorAction SilentlyContinue
    }
}

# Policy: Blocked websites
# Name: B_WebsiteFilter_Block
# Scope: Machine
# State: Enabled
# Source: firefox.admx

Clear-RegistryKeyValues -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox\WebsiteFilter\Block'

History 93 retained releases

6.69 Jan 2025
- Translations changed; choose a language above to compare its wording.
6.526 Nov 2024
- Translations changed; choose a language above to compare its wording.
6.011 Jul 2024
- Translations changed; choose a language above to compare its wording.
4.126 Jun 2023
- Option “Website Filter (JSON)” ~~[was: WebsiteFilter]~~[now: Website Filter (JSON)]
4.418 Oct 2022
- Translations changed; choose a language above to compare its wording.
3.48 Dec 2021
- Translations changed; choose a language above to compare its wording.
2.1019 Apr 2021
- Translations changed; choose a language above to compare its wording.
2.823 Feb 2021
- Translations changed; choose a language above to compare its wording.
2.725 Jan 2021
- Translations changed; choose a language above to compare its wording.
2.517 Nov 2020
- Description … indicate sites to be blocked. The match patterns are documented at https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Match_patterns. ~~[removed: Only http/https addresses are supported at the moment. ]~~There is a 1000 entry limit. If this policy is disabled or …
  Whole description, marked
  If this policy is enabled, you can specify match patterns that indicate sites to be blocked. The match patterns are documented at https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Match_patterns. ~~[removed: Only http/https addresses are supported at the moment. ]~~There is a 1000 entry limit. If this policy is disabled or not configured, no websites are blocked.
1.174 Jun 2020
- Translations changed; choose a language above to compare its wording.
1.158 Apr 2020
- Translations changed; choose a language above to compare its wording.
1.113 Dec 2019
- Translations changed; choose a language above to compare its wording.
1.1023 Oct 2019
- Translations changed; choose a language above to compare its wording.
1.8.229 Jul 2019
- Translations changed; choose a language above to compare its wording.
1.414 Dec 2018
- Description … If this policy is disabled or not configured, no websites are blocked.~~[removed: Starting with Firefox 62, this policy will only work from Computer Configuration.]~~
  Whole description, marked
  If this policy is enabled, you can specify match patterns that indicate sites to be blocked. The match patterns are documented at https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Match_patterns. Only http/https addresses are supported at the moment. There is a 1000 entry limit. If this policy is disabled or not configured, no websites are blocked.~~[removed: Starting with Firefox 62, this policy will only work from Computer Configuration.]~~
- Supported on Firefox 60 [added: or later, Firefox 60 ]ESR or later
- Supported on SUPPORTED_FF60~~[removed: ESR]~~; resolved; Blank;
1.317 Oct 2018
- Translations changed; choose a language above to compare its wording.
1.211 Sep 2018
- Description … to be blocked. The match patterns are documented at https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Match_patterns. Only http/https a~~[removed: cc]~~[added: ddr]esses are supported at the moment. There is a 1000 entry limit.~~[removed: ",]~~ If this policy is disabled or not configured, no websites are blocked.[added: Starting with Firefox 62, this policy will only work from Computer Configuration.]
  Whole description, marked
  If this policy is enabled, you can specify match patterns that indicate sites to be blocked. The match patterns are documented at https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Match_patterns. Only http/https a~~[removed: cc]~~[added: ddr]esses are supported at the moment. There is a 1000 entry limit.~~[removed: ",]~~ If this policy is disabled or not configured, no websites are blocked.[added: Starting with Firefox 62, this policy will only work from Computer Configuration.]
- Supported on ~~[removed: Microsoft Windows XP SP2]~~[added: Firefox 60 ESR] or later
- Supported on SUPPORTED_~~[removed: WINXPSP2]~~[added: FF60ESR]; resolved; Blank;
1.09 May 2018
- Already present in the first release ChangeIntel keeps.

74 later releases left it unchanged.

Template

Internal name: B_WebsiteFilter_Block
Namespace: Mozilla.Policies.Firefox
Template file: firefox.admx
Release: Mozilla Firefox 8.4 · file set a495190075c2a974…

Definition, editor controls and support

Definition

<policy class="Both" displayName="$(string.WebsiteFilter_Block)" explainText="$(string.WebsiteFilter_Block_Explain)" key="Software\Policies\Mozilla\WebsiteFilter\Block" name="B_WebsiteFilter_Block" presentation="$(presentation.WebsiteFilter)" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Mozilla.Policies.Firefox:firefox" />
      <supportedOn ref="Mozilla.Policies.Firefox:SUPPORTED_FF60" />
      <elements>
        <list id="WebsiteFilter" key="Software\Policies\Mozilla\Firefox\WebsiteFilter\Block" valuePrefix="" />
      </elements>
    </policy>

Editor controls

<presentation id="WebsiteFilter" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
        <listBox refId="WebsiteFilter" />
      </presentation>

Supported platforms and category

Mozilla.Policies.Firefox:category:firefox
<category displayName="$(string.firefox)" name="firefox" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Mozilla.Policies:Cat_Mozilla" />
    </category>
Mozilla.Policies.Firefox:definition:SUPPORTED_FF60
<definition displayName="$(string.SUPPORTED_FF60)" name="SUPPORTED_FF60" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
Mozilla.Policies:category:Cat_Mozilla
<category displayName="$(string.mozilla)" name="Cat_Mozilla" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
Mozilla.Policies.Firefox:category:firefox
<category displayName="$(string.firefox)" name="firefox" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Mozilla.Policies:Cat_Mozilla" />
    </category>
<strings><string id="Mozilla.Policies.Firefox:firefox">Firefox</string></strings>
Mozilla.Policies.Firefox:definition:SUPPORTED_FF60
<definition displayName="$(string.SUPPORTED_FF60)" name="SUPPORTED_FF60" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
<strings><string id="Mozilla.Policies.Firefox:SUPPORTED_FF60">Firefox 60 or later, Firefox 60 ESR or later</string></strings>
Mozilla.Policies:category:Cat_Mozilla
<category displayName="$(string.mozilla)" name="Cat_Mozilla" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
<strings><string id="Mozilla.Policies:mozilla">Mozilla</string></strings>