Define the maximum size of downloaded files and attachments to be scanned
Verified with Windows 11 25H2 — updated on July 30, 2026
Supported on: At least Windows Server 2012, Windows 8 or Windows RT
Path in the GPO console
Computer Configuration\Administrative Templates\Windows Components\Microsoft Defender Antivirus\Real-time Protection Description
This policy setting defines the maximum size (in kilobytes) of downloaded files and attachments that will be scanned. If you enable this setting, downloaded files and attachments smaller than the size specified will be scanned. If you disable or do not configure this setting, a default size will be applied.
Registry
HKLM
Software\Policies\Microsoft\Windows Defender\Real-Time Protection Value name: IOAVMaxSize
MDM / Intune (CSP)
./Device/Vendor/MSFT/Policy/Config/ADMX_MicrosoftDefenderAntivirus/RealtimeProtection_IOAVMaxSize Microsoft Learn documentation Mapping data: Microsoft Learn (CC BY 4.0)
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. ⓘ
.reg file
Windows Registry Editor Version 5.00
; Exported from gporais.com
; Policy: Define the maximum size of downloaded files and attachments to be scanned
; State: Enabled
; Supported on: At least Windows Server 2012, Windows 8 or Windows RT
[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\Real-Time Protection]
"IOAVMaxSize"=dword:00000001
"IOAVMaxSize"=dword:00005000More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Define the maximum size of downloaded files and attachments to be scanned
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
$path = 'HKLM:\Software\Policies\Microsoft\Windows Defender\Real-Time Protection'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'IOAVMaxSize' -Value 1 -Type DWord
Set-ItemProperty -Path $path -Name 'IOAVMaxSize' -Value 20480 -Type DWordIntune XML
OMA-URI: ./Device/Vendor/MSFT/Policy/Config/ADMX_MicrosoftDefenderAntivirus/RealtimeProtection_IOAVMaxSize
Data type: String
Value:
<enabled/>
<data id="RealtimeProtection_IOAVMaxSize" value="20480"/>Intune Remediation
# === Detection script ===
# Exported from gporais.com
# Policy: Define the maximum size of downloaded files and attachments to be scanned
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
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
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\Real-Time Protection' -Name 'IOAVMaxSize' -Expected 1 -Kind DWord)
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\Real-Time Protection' -Name 'IOAVMaxSize' -Expected 20480 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Define the maximum size of downloaded files and attachments to be scanned
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
$path = 'HKLM:\Software\Policies\Microsoft\Windows Defender\Real-Time Protection'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'IOAVMaxSize' -Value 1 -Type DWord
Set-ItemProperty -Path $path -Name 'IOAVMaxSize' -Value 20480 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Define the maximum size of downloaded files and attachments to be scanned
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
# 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: Define the maximum size of downloaded files and attachments to be scanned
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
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
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\Real-Time Protection' -Name 'IOAVMaxSize' -Expected 1 -Kind DWord)
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\Real-Time Protection' -Name 'IOAVMaxSize' -Expected 20480 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Define the maximum size of downloaded files and attachments to be scanned
# State: Enabled
# Supported on: At least Windows Server 2012, Windows 8 or Windows RT
$path = 'HKLM:\Software\Policies\Microsoft\Windows Defender\Real-Time Protection'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'IOAVMaxSize' -Value 1 -Type DWord
Set-ItemProperty -Path $path -Name 'IOAVMaxSize' -Value 20480 -Type DWordBuilding a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.