Disable new DMA devices when this computer is locked: registry value DisableExternalDMAUnderLockComputerHKLM\Software\Policies\Microsoft\FVE

Policy ID: DisableExternalDMAUnderLock_Name
Scope: Computer Configuration
Supported on: At least Windows Server 2016, Windows 10 Version 1703
Source: Administrative Templates (.admx) for Windows 11 2026 Update (26H2) (version 1.0)
Category: Windows Components › BitLocker Drive Encryption

Registry

DisableExternalDMAUnderLock

REG_DWORDComputer

HKLM\Software\Policies\Microsoft\FVE Current key

Enabled value: 1
Disabled value: 0

Apply with .reg · CMD · PowerShell

.reg

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\FVE]

; Options (use only one)
; Enabled
"DisableExternalDMAUnderLock"=dword:00000001
; Disabled
"DisableExternalDMAUnderLock"=dword:00000000

CMD

:: Options (use only one)

:: Enabled
reg add "HKLM\Software\Policies\Microsoft\FVE" /v "DisableExternalDMAUnderLock" /t REG_DWORD /d 1 /f
:: Disabled
reg add "HKLM\Software\Policies\Microsoft\FVE" /v "DisableExternalDMAUnderLock" /t REG_DWORD /d 0 /f

PowerShell

# Common: create the key
New-Item -Path 'HKLM:\Software\Policies\Microsoft\FVE' -Force | Out-Null

# Options (use only one)
# Enabled
New-ItemProperty -Path 'HKLM:\Software\Policies\Microsoft\FVE' -Name 'DisableExternalDMAUnderLock' -PropertyType DWord -Value 1 -Force | Out-Null
# Disabled
New-ItemProperty -Path 'HKLM:\Software\Policies\Microsoft\FVE' -Name 'DisableExternalDMAUnderLock' -PropertyType DWord -Value 0 -Force | Out-Null