Get BitLocker Recovery From Active Directory with Powershell

At the company I currently work for we’ve been using BitLocker since Vista (although Vista install base was rather small). Having moved from another “Pretty Good” Disk encryption technology, one thing we struggled with was Recovery information. While the previous solution had its own server to store all recovery keys, BitLocker links these to the Computer Object. When that computer object is deleted, so is the key. This was a battle for us at first since we have automation in place to remove stale AD Accounts, but–at the time–did not have any method to backup that information. We immediately added a table to a database and as part of our cleanup would backup these Keys.

First: Why not MBAM?

I loosely touched on this in another post regarding TPM Backup information in AD and i’ll give the quick summary again. By the time MBAM cam around, we already had our backup system in place. This was added into a global utility that allowed our technicians to perform AD tasks without AD permissions (Create computer, reset, move ou, etc…). MBAM would have just been “another thing” for us to maintain and manage. With our custom tool and SCCM already in place, MBAM did not provide us any additional benefits. For those of you using MBAM, This may not be for you, however this still provides a great way to quickly grab the information for those ad-hoc requests.

As we move to upgrade our various automation from the tried-and-true VBScript to the ever-so-loved Powershell, Obtaining the BitLocker Recovery Information was an odd one. If you use the RSAT tools and pull up details of a computer object there is a “BitLocker Recovery tab”.

RecoveryB

Each BitLocker Recovery password is an object of the computer account object. The odd thing is that by doing a Get-ADComputer, Recovery information is not returned as a “property” like other items–and where I expected it. As usual, first step was to use a search engine and see what others had done. I found a few results that gave me what i wanted (notably this post) but didn’t like the way it was scripted. The snippet that does the work is here:

$objADObject = get-adobject -Filter * | Where-Object {$_.DistinguishedName -match $objComputer.Name -and $_.ObjectClass -eq "msFVE-RecoveryInformation"}

While this gets the job done it is slow and by slow i mean the combination of “-Filter *” and piping to “Where-Object” is looking at everything before seeing if its the item (droid) that I’m looking for. Recovery Key look-up for my system took approximately 15 seconds for the first result, and didnt finish processing until a few seconds after that.

Let’s step back and look at a BitLocker Recovery object (msFVE-RecoveryInformation); really lets justify the filter “$_.DistinguishedName -match $objComputer.Name”.

Each BitLocker Recovery object is of the Object Class: msFVE-RecoveryInformation. If you look at the DistinguishedName of an object we can see it stems from the Distinguished name of the computer object it is attached to:

DistinguishedName : CN=2014-10-20T13:10:38-06:00{E59D69FF-6A3B-42A6-89C0-57A0DA0E302A},CN=WIN7X86PC01,OU=swComputers,DC=swansonglab,DC=com

Unfortunately this is the best way (I’ve found) to tie a recovery object back to the computer account. For those curious, here is what’s contained in a msFVE-RecoveryInformation object:

CanonicalName : swansonglab.com/swComputers/WIN7X86PC01/2014-10-20T13:10:38-06:00{E59D69FF-6A3B-42A6-89C0-57A0DA0E302A}
CN : 2014-10-20T13:10:38-06:00{E59D69FF-6A3B-42A6-89C0-57A0DA0E302A}
Created : 10/20/2014 1:10:55 PM
createTimeStamp : 10/20/2014 1:10:55 PM
Deleted :
Description :
DisplayName :
DistinguishedName : CN=2014-10-20T13:10:38-06:00{E59D69FF-6A3B-42A6-89C0-57A0DA0E302A},CN=WIN7X86PC01,OU=swComputers,DC=swansonglab,DC=com
dSCorePropagationData : {12/31/1600 6:00:00 PM}
instanceType : 4
isDeleted :
LastKnownParent :
Modified : 10/20/2014 1:10:55 PM
modifyTimeStamp : 10/20/2014 1:10:55 PM
msFVE-KeyPackage : {136, 1, 0, 0...}
msFVE-RecoveryGuid : {255, 105, 157, 229...}
msFVE-RecoveryPassword : 465762-121880-049797-598411-533643-549890-128436-549736
msFVE-VolumeGuid : {146, 36, 120, 28...}
Name : 2014-10-20T13:10:38-06:00{E59D69FF-6A3B-42A6-89C0-57A0DA0E302A}
nTSecurityDescriptor : System.DirectoryServices.ActiveDirectorySecurity
ObjectCategory : CN=ms-FVE-RecoveryInformation,CN=Schema,CN=Configuration,DC=swansonglab,DC=com
ObjectClass : msFVE-RecoveryInformation
ObjectGUID : d0a15cc8-5f86-42ed-8942-633cec25b6b1
ProtectedFromAccidentalDeletion : False
sDRightsEffective : 15
showInAdvancedViewOnly : True
uSNChanged : 99936
uSNCreated : 99936
whenChanged : 10/20/2014 1:10:55 PM
whenCreated : 10/20/2014 1:10:55 PM

Remember in most cases getting recovery is searched by the GUID. This can be filtered on using Powershell with no problems or computer object linking. The example I’m looking at is getting all recovery objects attached to a computer account.

So my issues with the snippet above (using “-Filter *” and “Where-Object”), again, was time consuming. Since the Recovery Information objects are attached to a computer object we can simply use the computer account’s Distinguished Name as the search base for the command:

# Get Computer Object
> $computer = Get-ADComputer -Filter {Name -eq 'WIN7X86PC01'}

# Get all BitLocker Recovery Keys for that Computer. Note the 'SearchBase' parameter
> $BitLockerObjects = Get-ADObject -Filter {objectclass -eq 'msFVE-RecoveryInformation'} -SearchBase $computer.DistinguishedName -Properties 'msFVE-RecoveryPassword'

# Output the results!
> $BitLockerObjects
DistinguishedName : CN=2014-10-20T13:10:38-06:00{E59D69FF-6A3B-42A6-89C0-57A0DA0E302A},CN=WIN7X86PC01,OU=swCompute
rs,DC=swansong,DC=com
msFVE-RecoveryPassword : 465762-121880-049797-598411-533643-549890-128436-549736
Name : 2014-10-20T13:10:38-06:00{E59D69FF-6A3B-42A6-89C0-57A0DA0E302A}
ObjectClass : msFVE-RecoveryInformation
ObjectGUID : d0a15cc8-5f86-42ed-8942-633cec25b6b1

DistinguishedName : CN=2014-10-20T13:11:29-06:00{450547C6-675C-4A61-B276-17CC620D3885},CN=WIN7X86PC01,OU=swCompute
rs,DC=swansong,DC=com
msFVE-RecoveryPassword : 632126-201135-053504-485045-151657-139986-094820-137687
Name : 2014-10-20T13:11:29-06:00{450547C6-675C-4A61-B276-17CC620D3885}
ObjectClass : msFVE-RecoveryInformation
ObjectGUID : 8c3963ea-89ec-4b41-934b-ee6023d9d1e9

DistinguishedName : CN=2014-10-20T13:12:03-06:00{A29D2D47-89D6-4459-B106-40B1F62A04EF},CN=WIN7X86PC01,OU=swCompute
rs,DC=swansong,DC=com
msFVE-RecoveryPassword : 497178-478654-023111-302291-606034-162855-504163-720698
Name : 2014-10-20T13:12:03-06:00{A29D2D47-89D6-4459-B106-40B1F62A04EF}
ObjectClass : msFVE-RecoveryInformation
ObjectGUID : 4a72004e-e76e-4cb3-a828-152011b8b541

Hopefully this has provided some additional information on BitLocker Recovery keys and how to obtain them should you ever need to!

Enjoi!

Advertisements

2 thoughts on “Get BitLocker Recovery From Active Directory with Powershell

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s