Windows Components › Internet Explorer

Prevent bypassing SmartScreen Filter warnings about files that are not commonly downloaded from the Internet

Computer and userNative Intune settingDisableSafetyFilterOverrideForAppRepUnknown

Supported on At least Internet Explorer 9.0

25H2 · 1.0

What it does

This policy setting determines whether the user can bypass warnings from SmartScreen Filter. SmartScreen Filter warns the user about executable files that Internet Explorer users do not commonly download from the Internet. If you enable this policy setting, SmartScreen Filter warnings block the user. If you disable or do not configure this policy setting, the user can bypass SmartScreen Filter warnings.

What it writes

Hive: HKEY_LOCAL_MACHINE or HKEY_CURRENT_USER
Registry key: Software\Policies\Microsoft\Internet Explorer\PhishingFilter
Value name: PreventOverrideAppRepUnknown
When enabled: DWORD 1
When disabled: value removed

In Intune

Native Intune setting: Yes — Policy CSP

./Device/Vendor/MSFT/Policy/Config/InternetExplorer/DisableBypassOfSmartScreenWarningsAboutUncommonFilesInternetExplorer on Microsoft LearnADMX-backed: Windows ships this template, so it is set with the template's own values, without an import.Windows builds listed: 10.0.15063.
./User/Vendor/MSFT/Policy/Config/InternetExplorer/DisableBypassOfSmartScreenWarningsAboutUncommonFilesInternetExplorer on Microsoft LearnADMX-backed: Windows ships this template, so it is set with the template's own values, without an import.Windows builds listed: 10.0.15063.

From Microsoft's Policy CSP DDF files (DDF v2 Files, February 2026), read 18 Oct 2026.

Security baselines

Microsoft's Windows 11 v26H2 Security Baseline v2 sets this to Enabled, in its GPO “MSFT Internet Explorer 11 - Computer”.

Policy value PreventOverrideAppRepUnknown: Sets PreventOverrideAppRepUnknown to 1 (REG_DWORD).

Read from the registry.pol files in the baselines' GPO backups, downloaded from Microsoft's Security Compliance Toolkit. All baselines

Configure and deploy

Choose a state; 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\Microsoft\Internet Explorer\PhishingFilter]
"PreventOverrideAppRepUnknown"=dword:00000001

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: Prevent bypassing SmartScreen Filter warnings about files that are not commonly downloaded from the Internet
# Name: DisableSafetyFilterOverrideForAppRepUnknown
# Scope: Machine
# State: Enabled
# Source: inetres.admx

Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Internet Explorer\PhishingFilter' -Name 'PreventOverrideAppRepUnknown' -PropertyType 'DWord' -Value 1

These deployment candidates come from the ADMX template; they are separate from the native CSP mapping above.

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.

ADMX profile candidate (OMA-URI)

./Device/Vendor/MSFT/Policy/Config/ADMX_inetres/DisableSafetyFilterOverrideForAppRepUnknown

ADMX SyncML candidate

<SyncML xmlns="SYNCML:SYNCML1.2">
  <SyncBody>
    <Replace>
      <CmdID>1</CmdID>
      <Item>
        <Meta>
          <Format>chr</Format>
          <Type>text/plain</Type>
        </Meta>
        <Target>
          <LocURI>./Device/Vendor/MSFT/Policy/Config/ADMX_inetres/DisableSafetyFilterOverrideForAppRepUnknown</LocURI>
        </Target>
        <Data>&lt;enabled/&gt;</Data>
      </Item>
    </Replace>
    <Final/>
  </SyncBody>
</SyncML>

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: Prevent bypassing SmartScreen Filter warnings about files that are not commonly downloaded from the Internet
# Name: DisableSafetyFilterOverrideForAppRepUnknown
# Scope: Machine
# State: Enabled
# Source: inetres.admx

$isMatch = Test-RegistryValueEquals -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Internet Explorer\PhishingFilter' -Name 'PreventOverrideAppRepUnknown' -Kind 'DWord' -Expected 1
if (-not $isMatch) {
    $reasons.Add('Value mismatch: HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Internet Explorer\PhishingFilter\PreventOverrideAppRepUnknown') | 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: Prevent bypassing SmartScreen Filter warnings about files that are not commonly downloaded from the Internet
# Name: DisableSafetyFilterOverrideForAppRepUnknown
# Scope: Machine
# State: Enabled
# Source: inetres.admx

Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Internet Explorer\PhishingFilter' -Name 'PreventOverrideAppRepUnknown' -PropertyType 'DWord' -Value 1

History 5 retained releases

22H2 · 1.015 Jul 2024
- Already present in the first release ChangeIntel keeps.

4 later releases left it unchanged.

Template

Internal name: DisableSafetyFilterOverrideForAppRepUnknown
Namespace: Microsoft.Policies.InternetExplorer
Template file: inetres.admx
Release: Windows 11 25H2 · 1.0 · file set de4e49983ebd651f…

Definition, editor controls and support

Definition

<policy class="Both" displayName="$(string.DisableSafetyFilterOverrideForAppRepUnknown)" explainText="$(string.IE_ExplainDisableSafetyFilterOverrideForAppRepUnknown)" key="Software\Policies\Microsoft\Internet Explorer\PhishingFilter" name="DisableSafetyFilterOverrideForAppRepUnknown" valueName="PreventOverrideAppRepUnknown" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.InternetExplorer:InternetExplorer" />
      <supportedOn ref="Microsoft.Policies.InternetExplorer:SUPPORTED_IE9" />
    </policy>

Editor controls

Supported platforms and category

Microsoft.Policies.InternetExplorer:category:InternetExplorer
<category displayName="$(string.InternetExplorer)" explainText="$(string.IE_ExplainCat)" name="InternetExplorer" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.Windows:WindowsComponents" />
    </category>
Microsoft.Policies.InternetExplorer:definition:SUPPORTED_IE9
<definition displayName="$(string.SUPPORTED_IE9)" name="SUPPORTED_IE9" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
        <or>
          <range minVersionIndex="9" ref="Microsoft.Policies.Products:InternetExplorer" />
        </or>
      </definition>
Microsoft.Policies.Products:product:InternetExplorer
sha256:f287ee590cbba46b7a95511866303967b9370c7c7d81185659d675ca19b05d72
Microsoft.Policies.Windows:category:WindowsComponents
<category displayName="$(string.WindowsComponents)" explainText="$(string.WindowsComponents_Help)" name="WindowsComponents" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
Microsoft.Policies.InternetExplorer:category:InternetExplorer
<category displayName="$(string.InternetExplorer)" explainText="$(string.IE_ExplainCat)" name="InternetExplorer" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.Windows:WindowsComponents" />
    </category>
<strings><string id="Microsoft.Policies.InternetExplorer:IE_ExplainCat">Contains settings to configure Internet Explorer</string><string id="Microsoft.Policies.InternetExplorer:InternetExplorer">Internet Explorer</string></strings>
Microsoft.Policies.InternetExplorer:definition:SUPPORTED_IE9
<definition displayName="$(string.SUPPORTED_IE9)" name="SUPPORTED_IE9" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
        <or>
          <range minVersionIndex="9" ref="Microsoft.Policies.Products:InternetExplorer" />
        </or>
      </definition>
<strings><string id="Microsoft.Policies.InternetExplorer:SUPPORTED_IE9">At least Internet Explorer 9.0</string></strings>
Microsoft.Policies.Products:product:InternetExplorer
<product displayName="$(string.InternetExplorer)" name="InternetExplorer" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
        <majorVersion displayName="$(string.InternetExplorer30)" name="InternetExplorer30" versionIndex="3" />
        <majorVersion displayName="$(string.InternetExplorer40)" name="InternetExplorer40" versionIndex="4" />
        <majorVersion displayName="$(string.InternetExplorer50)" name="InternetExplorer50" versionIndex="5" />
        <majorVersion displayName="$(string.InternetExplorer60)" name="InternetExplorer60" versionIndex="6" />
        <majorVersion displayName="$(string.InternetExplorer70)" name="InternetExplorer70" versionIndex="7" />
        <majorVersion displayName="$(string.InternetExplorer80)" name="InternetExplorer80" versionIndex="8" />
        <majorVersion displayName="$(string.InternetExplorer90)" name="InternetExplorer90" versionIndex="9" />
        <majorVersion displayName="$(string.InternetExplorer100)" name="InternetExplorer100" versionIndex="10" />
        <majorVersion displayName="$(string.InternetExplorer110)" name="InternetExplorer110" versionIndex="11" />
      </product>
<strings><string id="Microsoft.Policies.Products:InternetExplorer">Internet Explorer</string><string id="Microsoft.Policies.Products:InternetExplorer100">Internet Explorer 10</string><string id="Microsoft.Policies.Products:InternetExplorer110">Internet Explorer 11</string><string id="Microsoft.Policies.Products:InternetExplorer30">Internet Explorer 3</string><string id="Microsoft.Policies.Products:InternetExplorer40">Internet Explorer 4</string><string id="Microsoft.Policies.Products:InternetExplorer50">Internet Explorer 5</string><string id="Microsoft.Policies.Products:InternetExplorer60">Internet Explorer 6</string><string id="Microsoft.Policies.Products:InternetExplorer70">Internet Explorer 7</string><string id="Microsoft.Policies.Products:InternetExplorer80">Internet Explorer 8</string><string id="Microsoft.Policies.Products:InternetExplorer90">Internet Explorer 9</string></strings>
Microsoft.Policies.Windows:category:WindowsComponents
<category displayName="$(string.WindowsComponents)" explainText="$(string.WindowsComponents_Help)" name="WindowsComponents" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
<strings><string id="Microsoft.Policies.Windows:WindowsComponents">Windows Components</string><string id="Microsoft.Policies.Windows:WindowsComponents_Help">Contains settings for operating system components.</string></strings>