BCD settings and BitLocker

Applies to

  • Windows 10

This topic for IT professionals describes the BCD settings that are used by BitLocker.

When protecting data at rest on an operating system volume, during the boot process BitLocker verifies that the security sensitive boot configuration data (BCD) settings have not changed since BitLocker was last enabled, resumed, or recovered.

BitLocker and BCD Settings

In Windows 7 and Windows Server 2008 R2, BitLocker validated nearly all BCD settings with the winload, winresume, and memtest prefixes. However, this high degree of validation caused BitLocker to go into recovery mode for benign setting changes, for example, when applying a language pack BitLocker would enter recovery.

In Windows 8, Windows Server 2012, and later operating systems BitLocker narrows the set of BCD settings validated to reduce the chance of benign changes causing a BCD validation problem. If you believe that there is a risk in excluding a particular BCD setting from the validation profile, you can increase BCD validation coverage to suit your validation preferences. Alternatively, if a default BCD setting is persistently triggering recovery for benign changes, then you can exclude that BCD setting from the validation profile.

When secure boot is enabled

Computers with UEFI firmware can use Secure Boot to provide enhanced boot security. When BitLocker is able to use Secure Boot for platform and BCD integrity validation, as defined by the Allow Secure Boot for integrity validation group policy setting, the Use enhanced Boot Configuration Data validation profile group policy is ignored.

One of the benefits of using Secure Boot is that it can correct BCD settings during boot without triggering recovery events. Secure Boot enforces the same BCD settings as BitLocker. Secure Boot BCD enforcement is not configurable from within the operating system.

Customizing BCD validation settings

To modify the BCD settings BitLocker validates the IT Pro will add or exclude BCD settings from the platform validation profile by enabling and configuring the Use enhanced Boot Configuration Data validation profile Group Policy setting.

For the purposes of BitLocker validation, BCD settings are associated with a specific set of Microsoft boot applications. BCD settings are either associated with a specific boot application or can apply to all boot applications by associating a prefix to the BCD setting entered in the Group Policy setting. Prefix values include:

  • winload
  • winresume
  • memtest
  • all

All BCD settings are specified by combining the prefix value with either a hexadecimal (hex) value or a “friendly name.”

The BCD setting hex value is reported when BitLocker enters recovery mode and is stored in the event log (event ID 523). The hex value uniquely identifies which BCD setting caused the recovery event.

You can quickly obtain the friendly name for the BCD settings on your computer by using the command “bcdedit.exe /enum all”.

Not all BCD settings have friendly names, for those settings the hex value is the only way to configure an exclusion policy.

When specifying BCD values in the Use enhanced Boot Configuration Data validation profile Group Policy setting, use the following syntax:

  • Prefix the setting with the boot application prefix
  • Append a colon ‘:’
  • Append either the hex value or the friendly name
  • If entering more than one BCD setting, you will need to enter each BCD setting on a new line

For example, either “winload:hypervisordebugport” or “winload:0x250000f4” yield the same value.

Setting that applies to all boot applications may be applied only to an individual application, however the reverse is not true. For example, one can specify either: “all:locale” or “winresume:locale”, but as the bcd setting “win-pe” does not apply to all boot applications, “winload:winpe” is valid, but “all:winpe” is not valid. The setting that controls boot debugging (“bootdebug” or 0x16000010) will always be validated and will have no effect if it is included in the provided fields.

Note: Take care when configuring BCD entries in the Group Policy setting. The Local Group Policy Editor does not validate the correctness of the BCD entry. BitLocker will fail to be enabled if the Group Policy setting specified is invalid.

Default BCD validation profile

The following table contains the default BCD validation profile used by BitLocker in Windows 8, Windows Server 2012, and later operating systems:

Hex Value Prefix Friendly Name
0x11000001 all device
0x12000002 all path
0x12000030 all loadoptions
0x16000010 all bootdebug
0x16000040 all advancedoptions
0x16000041 all optionsedit
0x16000048 all nointegritychecks
0x16000049 all testsigning
0x16000060 all isolatedcontext
0x1600007b all forcefipscrypto
0x22000002 winload systemroot
0x22000011 winload kernel
0x22000012 winload hal
0x22000053 winload evstore
0x25000020 winload nx
0x25000052 winload restrictapiccluster
0x26000022 winload winpe
0x26000025 winload lastknowngood
0x26000081 winload safebootalternateshell
0x260000a0 winload debug
0x260000f2 winload hypervisordebug
0x26000116 winload hypervisorusevapic
0x21000001 winresume filedevice
0x22000002 winresume filepath
0x26000006 winresume debugoptionenabled

Full list of friendly names for ignored BCD settings

This following is a full list of BCD settings with friendly names which are ignored by default. These settings are not part of the default BitLocker validation profile, but can be added if you see a need to validate any of these settings before allowing a BitLocker–protected operating system drive to be unlocked.

Note: Additional BCD settings exist that have hex values but do not have friendly names. These settings are not included in this list.

Hex Value Prefix Friendly Name
0x12000004 all description
0x12000005 all locale
0x12000016 all targetname
0x12000019 all busparams
0x1200001d all key
0x1200004a all fontpath
0x14000006 all inherit
0x14000008 all recoverysequence
0x15000007 all truncatememory
0x1500000c all firstmegabytepolicy
0x1500000d all relocatephysical
0x1500000e all avoidlowmemory
0x15000011 all debugtype
0x15000012 all debugaddress
0x15000013 all debugport
0x15000014 all baudrate
0x15000015 all channel
0x15000018 all debugstart
0x1500001a all hostip
0x1500001b all port
0x15000022 all emsport
0x15000023 all emsbaudrate
0x15000042 all keyringaddress
0x15000047 all configaccesspolicy
0x1500004b all integrityservices
0x1500004c all volumebandid
0x15000051 all initialconsoleinput
0x15000052 all graphicsresolution
0x15000065 all displaymessage
0x15000066 all displaymessageoverride
0x15000081 all logcontrol
0x16000009 all recoveryenabled
0x1600000b all badmemoryaccess
0x1600000f all traditionalkseg
0x16000017 all noumex
0x1600001c all dhcp
0x1600001e all vm
0x16000020 all bootems
0x16000046 all graphicsmodedisabled
0x16000050 all extendedinput
0x16000053 all restartonfailure
0x16000054 all highestmode
0x1600006c all bootuxdisabled
0x16000072 all nokeyboard
0x16000074 all bootshutdowndisabled
0x1700000a all badmemorylist
0x17000077 all allowedinmemorysettings
0x22000040 all fverecoveryurl
0x22000041 all fverecoverymessage
0x31000003 all ramdisksdidevice
0x32000004 all ramdisksdipath
0x35000001 all ramdiskimageoffset
0x35000002 all ramdisktftpclientport
0x35000005 all ramdiskimagelength
0x35000007 all ramdisktftpblocksize
0x35000008 all ramdisktftpwindowsize
0x36000006 all exportascd
0x36000009 all ramdiskmcenabled
0x3600000a all ramdiskmctftpfallback
0x3600000b all ramdisktftpvarwindow
0x21000001 winload osdevice
0x22000013 winload dbgtransport
0x220000f9 winload hypervisorbusparams
0x22000110 winload hypervisorusekey
0x23000003 winload resumeobject
0x25000021 winload pae
0x25000031 winload removememory
0x25000032 winload increaseuserva
0x25000033 winload perfmem
0x25000050 winload clustermodeaddressing
0x25000055 winload x2apicpolicy
0x25000061 winload numproc
0x25000063 winload configflags
0x25000066 winload groupsize
0x25000071 winload msi
0x25000072 winload pciexpress
0x25000080 winload safeboot
0x250000a6 winload tscsyncpolicy
0x250000c1 winload driverloadfailurepolicy
0x250000c2 winload bootmenupolicy
0x250000e0 winload bootstatuspolicy
0x250000f0 winload hypervisorlaunchtype
0x250000f3 winload hypervisordebugtype
0x250000f4 winload hypervisordebugport
0x250000f5 winload hypervisorbaudrate
0x250000f6 winload hypervisorchannel
0x250000f7 winload bootux
0x250000fa winload hypervisornumproc
0x250000fb winload hypervisorrootprocpernode
0x250000fd winload hypervisorhostip
0x250000fe winload hypervisorhostport
0x25000100 winload tpmbootentropy
0x25000113 winload hypervisorrootproc
0x25000115 winload hypervisoriommupolicy
0x25000120 winload xsavepolicy
0x25000121 winload xsaveaddfeature0
0x25000122 winload xsaveaddfeature1
0x25000123 winload xsaveaddfeature2
0x25000124 winload xsaveaddfeature3
0x25000125 winload xsaveaddfeature4
0x25000126 winload xsaveaddfeature5
0x25000127 winload xsaveaddfeature6
0x25000128 winload xsaveaddfeature7
0x25000129 winload xsaveremovefeature
0x2500012a winload xsaveprocessorsmask
0x2500012b winload xsavedisable
0x25000130 winload claimedtpmcounter
0x26000004 winload stampdisks
0x26000010 winload detecthal
0x26000024 winload nocrashautoreboot
0x26000030 winload nolowmem
0x26000040 winload vga
0x26000041 winload quietboot
0x26000042 winload novesa
0x26000043 winload novga
0x26000051 winload usephysicaldestination
0x26000054 winload uselegacyapicmode
0x26000060 winload onecpu
0x26000062 winload maxproc
0x26000064 winload maxgroup
0x26000065 winload groupaware
0x26000070 winload usefirmwarepcisettings
0x26000090 winload bootlog
0x26000091 winload sos
0x260000a1 winload halbreakpoint
0x260000a2 winload useplatformclock
0x260000a3 winload forcelegacyplatform
0x260000a4 winload useplatformtick
0x260000a5 winload disabledynamictick
0x260000b0 winload ems
0x260000c3 winload onetimeadvancedoptions
0x260000c4 winload onetimeoptionsedit
0x260000e1 winload disableelamdrivers
0x260000f8 winload hypervisordisableslat
0x260000fc winload hypervisoruselargevtlb
0x26000114 winload hypervisordhcp
0x21000005 winresume associatedosdevice
0x25000007 winresume bootux
0x25000008 winresume bootmenupolicy
0x26000003 winresume customsettings
0x26000004 winresume pae
0x25000001 memtest passcount
0x25000002 memtest testmix
0x25000005 memtest stridefailcount
0x25000006 memtest invcfailcount
0x25000007 memtest matsfailcount
0x25000008 memtest randfailcount
0x25000009 memtest chckrfailcount
0x26000003 memtest cacheenable
0x26000004 memtest failuresenabled