Configure the 'Block at First Sight' feature
Verified with Windows 11 25H2 — updated on July 30, 2026
Supported on: At least Windows Server 2016, Windows 10
Path in the GPO console
Computer Configuration\Administrative Templates\Windows Components\Microsoft Defender Antivirus\MAPS Description
This feature ensures the device checks in real time with the Microsoft Active Protection Service (MAPS) before allowing certain content to be run or accessed. If this feature is disabled, the check will not occur, which will lower the protection state of the device. Enabled – The Block at First Sight setting is turned on. Disabled – The Block at First Sight setting is turned off. This feature requires these Group Policy settings to be set as follows: MAPS -> The “Join Microsoft MAPS” must be enabled or the “Block at First Sight” feature will not function. MAPS -> The “Send file samples when further analysis is required” should be set to 1 (Send safe samples) or 3 (Send all samples). Setting to 0 (Always Prompt) will lower the protection state of the device. Setting to 2 (Never send) means the “Block at First Sight” feature will not function. Real-time Protection -> The “Scan all downloaded files and attachments” policy must be enabled or the “Block at First Sight” feature will not function. Real-time Protection -> Do not enable the “Turn off real-time protection” policy or the “Block at First Sight” feature will not function.
Registry
Software\Policies\Microsoft\Windows Defender\Spynet Value name: DisableBlockAtFirstSeen
Enabled: DisableBlockAtFirstSeen = 0
Disabled: DisableBlockAtFirstSeen = 1
MDM / Intune (CSP)
./Device/Vendor/MSFT/Policy/Config/ADMX_MicrosoftDefenderAntivirus/DisableBlockAtFirstSeen 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: Configure the 'Block at First Sight' feature
; State: Enabled
; Supported on: At least Windows Server 2016, Windows 10
[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\Spynet]
"DisableBlockAtFirstSeen"=dword:00000000More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Configure the 'Block at First Sight' feature
# State: Enabled
# Supported on: At least Windows Server 2016, Windows 10
$path = 'HKLM:\Software\Policies\Microsoft\Windows Defender\Spynet'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'DisableBlockAtFirstSeen' -Value 0 -Type DWordIntune XML
OMA-URI: ./Device/Vendor/MSFT/Policy/Config/ADMX_MicrosoftDefenderAntivirus/DisableBlockAtFirstSeen
Data type: String
Value:
<enabled/>Intune Remediation
# === Detection script ===
# Exported from gporais.com
# Policy: Configure the 'Block at First Sight' feature
# State: Enabled
# Supported on: At least Windows Server 2016, Windows 10
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
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\Spynet' -Name 'DisableBlockAtFirstSeen' -Expected 0 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Configure the 'Block at First Sight' feature
# State: Enabled
# Supported on: At least Windows Server 2016, Windows 10
$path = 'HKLM:\Software\Policies\Microsoft\Windows Defender\Spynet'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'DisableBlockAtFirstSeen' -Value 0 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Configure the 'Block at First Sight' feature
# State: Enabled
# Supported on: At least Windows Server 2016, Windows 10
# 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: Configure the 'Block at First Sight' feature
# State: Enabled
# Supported on: At least Windows Server 2016, Windows 10
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
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\Spynet' -Name 'DisableBlockAtFirstSeen' -Expected 0 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Configure the 'Block at First Sight' feature
# State: Enabled
# Supported on: At least Windows Server 2016, Windows 10
$path = 'HKLM:\Software\Policies\Microsoft\Windows Defender\Spynet'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'DisableBlockAtFirstSeen' -Value 0 -Type DWordBuilding a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.