Posted in Other Site Links

Windows XP Power Management and Group Policy Preferences Behaviour Explained

Ever wondered why the behaviour of Group Policy Preferences Power Plan never worked the way you expected? Well Ned Pyle from Microsoft has written a really good article explaining this behaviour. http://blogs.technet.com/askds/archive/2009/12/11/windows-xp-power-management-and-group-policy-preferences.aspx

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Posted in Site News

Group Policy Videos

Just added a video section that has links to numerous online videos relating to group policy. To view it click on “Videos” in the navigation bar or just follow this link http://www.grouppolicy.biz/videos/ Be sure to check out my TechEd Australia 2009 video (see below) that was selected to be available for viewing without a login.

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Posted in News

Microsoft release two new Group Policy hot fixes

Microsoft just released two new hot fixes for the Group Policy Preferences (GPP) client-side extensions and the Group Policy Management Console (GPMC). Group Policy preferences client-side extension hotfix rollup for Windows Vista This hotfix resolves numerous issues with the client-side extensions for Vista and required Service Pack 1 or 2 to be installed. Download from http://support.microsoft.com/?kbid=977983 You cannot create a…

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Posted in Setting of the Week

Group Policy Setting of the Week 9 – Allow Automatic Updates immediate installation

First of all thank you for coming to my new web site www.grouppolicy.biz this site is still rather new and if you have any issues and/or suggesting please feel free to post a comment. This weeks GPSW covers another product that I use a lot and love to talk about, Windows Server Update Services (a.k.a. WSUS). The “Allow Automatic Updates…

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Posted in Best Practice Security Tutorials

How to use Group Policy Preferences to change account Passwords

If you are using the Group Policy Preferences to apply local user account be aware there is a security risk in doing this. In short the passwords are stored in the AD SYSVOL encrypted using AES however the encryption key is well known so this could only be considered obfuscated at best…. More info about this can be read at http://blogs.technet.com/grouppolicy/archive/2009/04/22/passwords-in-group-policy-preferences-updated.aspx

However using Group Policy Preferences to set passwords on local user accounts is still extremely useful and one could argue that not changing the local administrator account password is potentially more of a security issue over time. So if you still want to use this option but want to mitigate the risk in using this feature then here are a few steps that can be taken that will help.

Before you start tell as few as people as possible when you are changing the passwords. This is important as if you tell people when the password is changing they will know when to look for the password stored in the SYSVOL.

Step 1. Change default group policy refresh period to be as short as you dare (see Image 1). The default is 90 minutes but if you can safely crank it down 5 or 10 minutes that would be better. This will speed up the propagation delay of the new password once is configured in the group policy.

Image 1. Changing the default group policy refresh

Step 2. Some time during the middle of the day create a new group policy object and configured the the new local user password option (See image 2). then wait for the setting to propagate.

Image 2. Configuring the Local Account Password

Step 3. Then you need to wait… How long? The formula i would use for the time to wait is as follows:

Max Active Directory Propagation Delay + Max Group Policy Refresh Interval

Therefore if it take 16 minutes for Group Policy changes to propagate to all DC’s in the domain and you have set group policy refresh to 10 minutes the formula will look like this.

16 minutes + (10 minutes + 2 minutes) = 28 minutes

Note the 2 minutes is to take into account the 20% offset that group policy refresh interval has from the set value.

Step 4. Then one you have waited for the new password setting to rollout DELETE the group policy password setting you configured. This will purge the obfuscated version of the password from the SYSVOL. The reason also I recommend you create and delete a new group policy each time you do this is so the password file is store in a different path in the SYSVOL which is just another way to make it harder for someone to file the password file.

Step 5. You may want to repeat steps 4, 5 and 6 a couple of days apart to ensure that you have applied the setting to all the computers that were not turned on or connected to the network the first time (sounds like a great reason to deploy Direct Access).

Step 6. Finally don’t forget to wind back the default group policy refresh interval to its original value.

Now as we are all good IT Professional it would be best to tell people that the local admin password has changed and will be disseminated securely (NOT via email or IM) when needed. The key is to do it quick and then remove the policy as soon as you are done to have the smallest window of opportunity as possible for someone to grab the password file.

Of course this sound very devious and some could say you are covering your trails by deleting the policy once you are done which is not something you generally want to do as a good IT Professional… But if you are going to do this in a organisation then your are probably going to need to follow change control anyway so you should still have an official record of what you have done.

Alan Burchill

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Posted in Best Practice Security Tutorials

How to configure Group Policy to use Data Recovery Agents with “Bitlocker to Go” drives – Part 2

As I previously mentioned in Part 1 “use Group Policy to save “How to use BitLocker to Go” recovery keys in Active Directory – Part 1” one of the cool new features in Windows 7 is the ability to encrypt removable storage devices to help prevent the loss of data within an organisation while storing a copy of the decryption key in Active Directory. Another way to encrypt the removable storage devices and still have the ability to recover a encrypted devices if the unlock key is lost is to use a Data Recovery Agent digital certificate.

Now before you begin you first need to have deployed you a PKI infrastructure in your organisation so that you can issue the data recovery certificate to your nominated recovery agents.

So lets get started…

How to configured Group Policy to use a Data Recovery Agent with “BitLocker to Go” drives

Issuing the EFS Data Recovery Agent

First you need to create/issue at least one account with the Data Recovery Agent certificate that will be used for when encrypting all the Bitlocker to Go drives.

Step 1. Click Start, and then type certmgr.msc to open the Certificates snap-in

Step 2. In the console tree, expand Personal, and then click Certificates.

Step 2. Right click on Certificates and click on All Tasks and then Request New Certificate…

Step 3. Click Next to the first page of the Certificate Enrollment wizard and then then click on Active Directory Enrollment Policy and click Next

Step 4. Tick the EFS Recovery Agent policy and then click Enroll

Step 5. Click Finish once your account has enrolled as the EFS Recovery Agent certificate.

You should now see the File Recovery Certificate in you Personal Certificate store.

Exporting the DRA Certificate

You now need to export the DRA certification information to be used in the BitLocker Drive Encryption group policy in a future step.

Step 1. Double-click the BitLockerDRA certificate to display the certificate properties sheet.

Step 2. Click the Details tab

Step 3. Click Copy to File

Step 4. Click Next on the Welcome to the Certificate Export Wizard page

Step 5. Leave the No, do not export the private key selected and then click Next.

Step 6. On the Export File Format page, verify that DER encoded binary x.509 (.CER) is selected, and then click Next.

Step 7. On the File to Export page, click Browse to display the Save as dialog box. In File name, type BitLocker. In Save as type, verify that DER Encoded Binary X.509 (.cer) is selected, and then click Save to return to the File to Export page.

Step 8. The File name box on the wizard page should now display the path to the BitLocker.cer file in your document library. Click Next.

Step 9. On the Completing the Certificate Export Wizard page, verify that the information displayed is correct, and then click Finish.

Step 10. When the certificate has been exported, the Certificate Export Wizard dialog box will be displayed with the message The export was successful. Click Close to close the dialog and the wizard.

Configuring the Bitlocker Data Recovery Agent in Group Policy

In this section we are going to take the Data Recover Agent certificate we exported above and import it into the group policy to apply to computers that will have DRA certification for encrypting Bitlocker drives. The screenshots below are from a Windows Server 2008 R2 server with the group policy management console installed but if you are on a Windows 7 computer you will need to have install the Remote Server Admin Tools installed.

Step 1. Click Start, type gpedit.msc in the Search programs and files box, and then press ENTER.

Step 2. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Yes.

Step 3. In the console tree under Local Computer Policy\Computer Configuration\Windows Settings\Security Settings\Public Key Policies, right-click BitLocker Drive Encryption, and then click Add Data Recovery Agent to start the Add Recovery Agent Wizard.

Step 4. Click Next on the Add Recovery Agent Wizard welcome screen

Step 5. On the Select Recovery Agents page, click Browse Folder

Step 6. Browse to the location you have a copy of the BitLocker.cer file that you exported in the previous procedure select the certificate and click Open

Step 7. Click

Note: You can repeat this process as necessary to add multiple data recovery agents. After all data recovery agent certificates you want to use have been specified, click Next.

Note: The example above has USER_UNKNOWN because the DRA file was manually imported.

Step 8. On the Completing the Recovery Agent Wizard page, click Finish to add the data recovery agent

Below is the BitLocker Drive Encryption setup with a DRA installed.

Additional Group Policy Configuration

BitLocker Identification Field

You now need to configure the BitLocker Identification field on all the computers you are going to use Bitlocker on as this helps identify what removable devices belong to your organisation.

Step 1. Click Start, type gpedit.msc in the Search programs and files box, and then press ENTER.

Step 2. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Yes.

Step 3. In the console tree under Computer Configuration\Administrative Templates\Windows Components\Bitlocker Drive Encryption and then double click on Provide the unique identifiers for your organization

Step 3. Enter you specific Bitlocker identification name that you use to identify your Bitlocker encrypted devices in the BitLocker identification field

Note: You can add additional Bitlocker identifiers from other trusted organisations in the Allowed BitLocker identification field

Enable Allow Data Recovery Agent

Continuing on from above you will need to configure you computers to Allow the Data Recovery Agent option.

Step 4 (cont.). In the console tree under Computer Configuration\Administrative Templates\Windows Components\Bitlocker Drive Encryption\Removable Data Drive and then double click on Choose how Bitlocker-protected removable drives can be recovered , then you will need to click Enabled and tick Allow data recovery agent then click OK

Note: You still have the option of configuring the standard AD recovery keys in this window. The Allow Data Recovery Agent option as far as I can tell has no bearing of the other options.

You have now configured Group Policy to use a Data Recovery Agent certificate to be used to encrypt all the “Bitlocker to Go” drives in your organisation.

How to unlock a “BitLocker to Go” drive with a Data Recovery Agent

Below are the instructions explaining how to use the Data Recovery Agent to unlock a BitLocker to Go encrypted drive

Step 1. Put the drive into the computer you want to unlock.

Step 2. Right Click on a Command Prompt, and then click Run as administrator. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Yes.

Step 3 (optional). If you want to get information on the volume before you unlock it you can run manage-bde -status E:

Step 4. Now you need to get the “CertificateThumbprint” of the drive you want to unlock type the command manage-bde –protectors –get E: where E: is the volume you are trying to unlock

Note: Take a note of the Data Recovery Agent (Certificate Based) Certificate Thumbprint (see circled in red).

Tip: You could also mark the thumbprint by using the Edit > Mark option of the command prompt.

Then select the thumbprint by clicking on the first character of the thumbprint and dragging to the last character.

Step 4. To unlock the drive, type the following command Manage-bde –unlock E: -cert –ct 88d07b2874031569e17eedf402e0a098fc0f7b81

You have now successfully unlocked the drive using a Data Recovery Agent.

Note: You will need to have the Data Recovery Agent Certificate (with the private key) installed in the Personal certificate store on the computer you are performing this task.

Step 5 (optional). Try getting running the following command again to view more information about the drives encryption manage-bde -status E:

Form more information about BitLocker drive encryption with Data Recovery Agents see the following pages:

Microsoft TechNet: Configuring the BitLocker Identification Field (Windows 7)
Microsoft TechNet: Using a Data Recovery Agent to Recover Bitlocker-Protected Drives
Microsoft TechNet: Using Data Recovery Agents with Bitlocker

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Posted in Best Practice Security Tutorials

How to use Group Policy to save “BitLocker to Go” recovery keys in Active Directory – Part 1

One of the cool new feature in Windows 7 Ultimate and Enterprise is the ability to encrypt USB devices with a password to protect the data from falling into the wrong hands. One of the problem with this is that if a user were to ever forget the unlock key then they will need to remember where they kept the recovery file or paper print out of the 48 digit recovery key. Now for a consumer this feature this might be fine as you keep can keep the key in a fire proof safe or even a locked filing cabinet but if you are managing this in a corporate environment you might have to keep track of thousands or even ten’s of thousands of these devices to keep track of the recovery key.

Well there is where group policy can be your saviour…. of course!

In Part 1 of this “how to” I am going to show you how to setup the recovery key archiving into Active Directory. In Part 2 I will show you how to use Group Policy with Active Directory Certificate Services to enable a Data Recovery Agent so that all your devices can be recovery using a single EFS recovery agent account.

Part 1

Using group policy you can mandate that all encrypted removable device must first have the recover key stored in Active Directory before they start to encrypt. This ensures that for any USB encrypted devices in your organisation that you will always have the ability to unlock the data on the drive even in case that someone forgets the unlock password.

Now before we begin there are a few pre-requisites that we need to cover to make sure this work.

1. You Active Directory must be running the Windows Server 2003 R2 scheme extensions. But I hear you say “you said that Group Policy Preferences doesn’t need schema changes to work” well yes… this is still true it is not a group policy requirement it is a BitLocker requirement.

2. You should install the “BitLocker Drive Encryption Administration Utilities” with Windows Server 2008 R2 or with the RSAT tools for Windows 7 (see image 1.) on at least one computer in your organisation. This computer can then be used to search for and view the recovery keys if you ever need them. This is a new tool with 2008 R2/Windows 7 and makes it MUCH easier to read the recovery keys than back in the 2003 R2/Vista days.

Image 1. Installing “BitLocker Drive Encryption Administration Utilities”

How to configured Group Policy to save the Recovery Key?

Now before I go on I will assume that you are already familiar with Group Policy so all I am going to cover is the key (pardon the pun) policies you need to ensure the recovery keys are backed up to AD DS for all your removable USB storage devices in your organisation.

Step 1. Edit the group policy that you have applied to all your workstations and navigate to Computer > Policies > Administrative Templates > Windows Components > BitLocker Drive Encryption > Removable Data Drives. Here the two policies you need to enable are “Deny write access to removable drives not protected by BitLocker” and “Choose how BitLocker-protected Removable drives can be recovered” (see Image 2).

Image 2. Removable Data Drives BitLocker Drive Group Policy

Step 2. When you Enable the “Deny write access to removable drives not protected by BitLocker” also tick the “Do not allow write access to devices configured in another organization” option (see Image 3). This setting is important as it will make any non-BitLocker encrypted devices from being written to in your organisation thus bypassing the whole reason to use BitLocker.

Image 3. Deny write access to removable drives not protected by BitLocker

Step 3. Now Enable the “Choose how BitLocker-protected Removable drives can be recovered” and make sure that the “Save BitLocker recovery information to AD DS for removable data drives” and the “Do not enable BitLocker until recovery information is stored to AD DS for removable data drives” are both ticked (See image 4.). This setting ensures the computer has successfully saved recovery key into AD before encrypting a USB storage device.

Image 4. Choose how BitLocker-protected removable drives can be recovered

You may also want to consider ticking the “Omit recovery option form the BitLocker setup wizard” as this will prevent you users from saving the recovery key manually which might be desirable if you don’t trust them to store the key in a safe place.

Because of the “Do not enable BitLocker until recovery information is stored to AD DS for removable data drives” option has been ticked if the user tries to encrypt a new USB storage device when not connected to the corporate network then they will get the following error message (see image 5).

Image 5. Error saving recovery key

If the user is out of the office they will need to establishing a VPN connection or enable BitLocker on the device the next time they are in the Office. This would not be a problem if you have configured Direct Access but this is a post for another time.

Note: The loop hole to this is that if someone already had a BitLocker to Go encrypted device and plugs it into a computer they will be able to save information to the device. This does not mean the data will not be encrypted its just you wont have the recovery key if they forget the password to that particular device.

To help with this problem you can set the BitLocker identification field on all the computers in the organisation so they will reject all encrypted devices that don’t have the same identification field value. This setting is under Computer > Policies > Administrative Templates > Windows Components > BitLocker Drive Encryption called “Provide the unique identifiers for your organization” (see image 6.). This might sound like you can mandate outside memory sticks can’t be used in your organisation but if someone has set the identification field to the same value this would get around option.

Image 6. Provide the unique identifiers for your organization

How to recover the BitLocker recovery password in AD?

So you have deployed BitLocker to your organisation and you have told everyone to be careful to remember the passwords but of course your manger has come to you saying that they have forgotten the password for his USB memory stick and it has the only copy of some really important files on it that he has have for a meeting tomorrow.

What do you do?

Step 1. First we need to identify the USB devices Recovery key identifier by plugging it into a computer running Windows 7 Ultimate/Enterprise. You can then find this identifier by clicking on the “I forgot my password” option (see image 7.)

Image 7. I forgot my password

Step 2. Then write down the 8 characters of the recovery key identifier (See image 8.)

Image 8. Recovery key identifier

Step 3. Now go to the computer that you installed the “BitLocker Recovery Password Viewer” tool that I previously mentioned above launch “Active Directly Users and Computers” MMC snap-in with and account with Domain Admin privileges. Click on the domain name that will have the recovery key saved and then click “Action” and then “Find BitLocker Recovery Password…” (see image 9.).

Image 9. “Find BitLocker Recovery Password…”

Step 4. Now type the first 8 characters you wrote down in step 2. and click “Search” (See Image 10.). This will show you the Recovery Password in the Details pane that you will need to unlock the drive.

Image 10. Find BitLocker Recovery Password…”

Step 5. Now go back to the computer you have plugged the USB device into and click on “Type the recovery key” (see image 7.).

Step 6. Now type the 48 digit Recovery Password into the text box and click “Next” (see image 11.)

Image 11. Enter your recovery key

Step 7. Click OK and you will now be able to read the required file off this drive (See Image 12.).

Image 12. You cannot save file on this drive

Note: If you want to restore the drive back to normal you will need to go to the control panel and go into the “Manage BitLocker” option to “Turn off BitLocker” (see Image 13.) on the device and then go back and select the option to “Turn On BitLocker” again. This will completely reset the recovery key on the device making the one you just recovered totally invalid.

Image 13. Control Panel BitLocker Drive Encryption option

Part 2 can now be found here “How to configure Group Policy to use Data Recovery Agent to encrypt “Bitlocker to Go” drives – Part 2”

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Posted in Best Practice Tutorials

How to use Group Policy Preferences to manage Windows Power Plans

One of the new feature of Group Policy Preferences in Windows 7 and Windows Server 2008 R2 is support for configuring power plans using preferences for Windows Vista and later (see Image 1). You used to be able to control power management in Vista using native policies however the advanced targeting of preferences now enables lot of new scenarios with power savings. AWSOME!

Image 1. Creating a new Windows Vista and Later Power Plan

One of the really neat things that you can do with Group Policy Preferences (GPP’s) and Targeting is change the power scheme of a computer based on the time of the day and the day of the week. This allows you to apply more aggressive power plans to your workstations after hours but then then back off during the day when people are working. Even though that Windows Vista (and Windows 7) support adaptive display time out which backs off the screen saver timeout when a user is still sitting at a computer but not actively using it they still have to wake up the computer by before the timeout started to back off. Applying the less aggressive power plan during working hours means that the user is less likely to have to keep waking up their computer in the first place as you have configured longer time out values.

Now if this sounds familiar you’d be right as I did demo some of this during my TechEd Australia Group Policies session that I did with Lilia Gutnik and it is similar to the TechNet Edge video by Michael Kleef and Mark Gray. But in this article I am going to diving a lot deeper than my demo or in the TechNet Edge video.

So before we talk about how to do this first lets go over what we are trying to achieve. We are assuming you manage a fleet of workstations that are only used during standard business hours and afterhours you want the computers to go to use as little as power as possible. You want to apply different power plans to the computers not only based on the day of the week but also the time of the day to make sure you get maximum possible power savings (see Image 2).

Image 2. Example power plan timetable

So to do this we setup two separate power plans, with one that is applied by default all the time and the other one that will take precedence and apply during business hours.

How to setup the Default Power Plan Policy

Step 1. Create a Power Plan under the User Configuration option of a GPO that has has aggressive power savings configured without any targeting other than being applied to all the users you want to control the power plans. I will leave the exact details of the power plan up to you but I will recommend that if you are going to set the “Sleep” timeout for Windows Vista (or greater) then make sure you also enable the “Allow hybrid sleep” option (even on your desktops) (see Image 3.) as this will protect your computers from data loss if you lose power to your office environment afterhours.

Image 3. Enable hybrid sleep mode

Step 2. Rename the item to be called something like “Default Power Plan” (see Image 4) and also make sure that it is always set to order number one.

WARNING – If you do this make sure you either immediately disable the item (tool bar > red circle “disable this item”) or setup the Business Hours Power Plan straight away so that you don’t start shutting down all your computer during the middle of the day.

Image 4. Default Power Plan at Order 1

How to setup the Business Hours Power Plan Policy

Step 3. Create another Power Plan setting item called “Business Hours Power Plan” (see Image 5.) making sure it is lower order than the default power plan. Again I will leave the exact settings up to you but this one should be less aggressive than your default power plan.

Image 5. Business Hours Power Plan

Step 4. Now go into the properties of the “Business Hours Power Plan”

Step 5. Click on the Common Tab and tick “Item-Level Targeting”

Step 6. Click on the targeting button

First of all we are going to create a collection that will target the Business House Power Plan to only the weekdays of the week.

Step 7. In the targeting Editor click on “Add Collection” (see Image 6.)

Image 6. Creating a targeting collection

Step 8. Click on the “New Item” and then click on “Date Match” (see Image 7 & 8.)

Image 7. Creating a Date Match rule

Image 8. Date match rule before being dragged into a Collection

Step 9. Now you will need to drag the “AND the day of the week is Sunday” onto the “the collection is true” and change the day to “Monday” (see Image 9.)

Image 9. Date Match rule after being dragged in the collection.

Step 10. Now make sure that “the day of the week is Monday” is highlighted and click CTRL-C once and CTRL-V four times to copy and paste the date match rule once for each weekday (see Image 10).

Image 10. Five date match rules in one collection

Step 11. Now click on each of the “AND the day of the week is Monday” and press F6 to change each date match rule from and “AND” to a “OR” and then change the days to Tuesday , Wednesday, Thursday and Friday (see Image 11).

Image 11. Data Range Collection configured to apply only during weekdays

Now we will add a Time Range option that will refine when we target the Business House Power Plan to just working hours of the weekdays.

Step 12. Click on the “this collection is true” and then click on “New Item” and then click on “Time Range” (see Image 12).

Image 12. Adding Time Range to targeting

Step 13. Now configured the time range to when during the day you want to Business Hours Power Plan to apply (see Image 13).

Note – Make sure you allow for the policy refresh interval (default 90 minutes with a 20% random offset) when configuring the start and end time. This means you might want to start applying the policy 2 hours before the start of business (e.g. 6:30am) to make sure all the computers are configured with the Business Hours Power Plan before people login in the morning (e.g. 8:30am).

Image 13. Targeting configured with Date Range collection and a Time Range

Now you have configured a Group Policy Preference to apply less aggressive power plans to your computer during business hours while still having more aggressive power plans applied after hours.

Other Option – More user Control

In the example above we just modified the “Balanced” power plan setting when we wanted to make changes to the power settings. If you did not want to give your users some more control and not force specific power plans you could just select the “High performance“ plan and tick “Set as the active power plan” for the Business Hours Power Plan (see Image 14) and the “Power Saver” plan as active in the Default Power plan (see Image 15).

Image 14. Setting the High Performance plan as active

Image 15. Setting the Power Saver plan as active

This way your users can still configure each of the power plans to their own preference but you will still make sure that the “Power Saver” plan will be applied to your computers after hours. However as you are only setting which plan is active then your users could get around the power plan as by configure both plans to never time out thus negating the benefit of any of the plan’s.

Other Options – Less aggressive Default Power Plan

You may also want to set the default power policy to be less aggressive by default and then apply the aggressive power as the second item in the list using a little more complicated targeting (see Image 16). The advantage of this method is you can easily turn off the aggressive power savings plan when you want to do afterhours by just disabling the “Afterhours Power Plan”.

Image 16. Targeting to apply plan only afterhours

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