Enable MIME Sniffing
Verified with Windows 11 25H2 — updated on July 23, 2026
Supported on: At least Internet Explorer 6.0 in Windows XP with Service Pack 2 or Windows Server 2003 with Service Pack 1
Path in the GPO console
Computer Configuration\Administrative Templates\Windows Components\Internet Explorer\Internet Control Panel\Security Page\Locked-Down Trusted Sites Zone User Configuration\Administrative Templates\Windows Components\Internet Explorer\Internet Control Panel\Security Page\Locked-Down Trusted Sites Zone Description
This policy setting allows you to manage MIME sniffing for file promotion from one type to another based on a MIME sniff. A MIME sniff is the recognition by Internet Explorer of the file type based on a bit signature. If you enable this policy setting, the MIME Sniffing Safety Feature will not apply in this zone. The security zone will run without the added layer of security provided by this feature. If you disable this policy setting, the actions that may be harmful cannot run; this Internet Explorer security feature will be turned on in this zone, as dictated by the feature control setting for the process. If you do not configure this policy setting, the actions that may be harmful cannot run; this Internet Explorer security feature will be turned on in this zone, as dictated by the feature control setting for the process.
Registry
Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Lockdown_Zones\2 Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Lockdown_Zones\2 Export Builder
BETAConfigure the state, scope and options, then generate .reg, PowerShell, Intune and SCCM outputs — or add the setting to a multi-setting collection.
These exports write the registry — this is not a managed GPO. ⓘ
Applying both scopes creates an ambiguous configuration (computer takes precedence over user). Only do this intentionally.
.reg file
Windows Registry Editor Version 5.00
; Exported from gporais.com
; Policy: Enable MIME Sniffing
; State: Enabled
; Scope: Computer (HKLM)
; Supported on: At least Internet Explorer 6.0 in Windows XP with Service Pack 2 or Windows Server 2003 with Service Pack 1
[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Lockdown_Zones\2]
"2100"=dword:00000003More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Enable MIME Sniffing
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: At least Internet Explorer 6.0 in Windows XP with Service Pack 2 or Windows Server 2003 with Service Pack 1
$path = 'HKLM:\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Lockdown_Zones\2'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name '2100' -Value 3 -Type DWordIntune XML
No direct Policy CSP / OMA-URI mapping for this policy. Use the Intune Remediation tab, or ingest the ADMX in Intune.Intune Remediation
# === Detection script ===
# Exported from gporais.com
# Policy: Enable MIME Sniffing
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: At least Internet Explorer 6.0 in Windows XP with Service Pack 2 or Windows Server 2003 with Service Pack 1
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Lockdown_Zones\2' -Name '2100' -Expected 3 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Enable MIME Sniffing
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: At least Internet Explorer 6.0 in Windows XP with Service Pack 2 or Windows Server 2003 with Service Pack 1
$path = 'HKLM:\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Lockdown_Zones\2'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name '2100' -Value 3 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Enable MIME Sniffing
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: At least Internet Explorer 6.0 in Windows XP with Service Pack 2 or Windows Server 2003 with Service Pack 1
# SCCM Configuration Item guidance:
# Create a Configuration Item of type "Setting: Script".
# Discovery script: use the Detection script below.
# Remediation script: use the Remediation script below.
# Compliance rule: the Discovery script output equals 'Compliant'.
# === Detection script ===
# Exported from gporais.com
# Policy: Enable MIME Sniffing
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: At least Internet Explorer 6.0 in Windows XP with Service Pack 2 or Windows Server 2003 with Service Pack 1
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Lockdown_Zones\2' -Name '2100' -Expected 3 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Enable MIME Sniffing
# State: Enabled
# Scope: Computer (HKLM)
# Supported on: At least Internet Explorer 6.0 in Windows XP with Service Pack 2 or Windows Server 2003 with Service Pack 1
$path = 'HKLM:\Software\Policies\Microsoft\Windows\CurrentVersion\Internet Settings\Lockdown_Zones\2'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name '2100' -Value 3 -Type DWordBuilding a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.