Getting Rid of Passwords in Azure AD / Office 365

Posted on 3 CommentsPosted in Authentication, Azure Active Directory, Azure AD, AzureAD, FIDO, modern authentication, Multi-Factor Authentication, password, yubikey

This article is based on the public preview of the use of hardware tokens/Microsoft Authenticator to do sign-in without passwords released in July 2019

Using Microsoft Authenticator for Passwordless Sign-in

You used to be able to do this by running the following in PowerShell for the last few years

New-AzureADPolicy -Type AuthenticatorAppSignInPolicy -Definition ‘{“AuthenticatorAppSignInPolicy”:{“Enabled”:true}}’ -isOrganizationDefault $true -DisplayName AuthenticatorAppSignIn

Interestingly, if you have done this in the past, the new Azure AD portal settings for doing this do not take this into consideration. So first, if you have run the above then you need to remove it with Remove-AzureADPolicy –Id <get the ID using Get-AzureADPolicy> before you implement the below, otherwise it is turned on for everyone even though Azure AD Portal says it is not enabled:

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So to start, visit the Azure AD Portal at https://portal.azure.com and select Azure Active Directory. Then select Authentication Methods (under Security) and then Authentication Method Policy (Preview) or go directly there with https://portal.azure.com/#blade/Microsoft_AAD_IAM/ActiveDirectoryMenuBlade/AuthenticationMethods.

Click Microsoft Authenticator passwordless sign-in and choose Enable and to pilot choose Select Users and the group you want to pilot with. Otherwise if you want to turn it on for all users, just leave the default. Note that nothing changes for the user – they need to do stuff before it works for them.

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As the notice says, also ensure that you have MFA with push notifications enabled. This option has been available for a year or so now, and you will find it on Password Reset > Authentication Methods (or directly with https://portal.azure.com/#blade/Microsoft_AAD_IAM/ActiveDirectoryMenuBlade/PasswordReset). This is not the same setting as the blue bar at the top of the page you are currently on.

For the user, from within Microsoft Authenticator, they need to go to the settings and register the device with their login. This is a one time process and once you have done the above and they have registered the device, they can choose to do password-less sign-in.

From a login perspective, it looks like this:

  1. Enter your username to an Azure AD login
  2. image
  3. On your phone, in the notification from the Microsoft Authenticator app, you select the displayed number (which changes number, and the position of the number each time)
  4. Screenshot_20190711-212252

Hardware Tokens Instead of Passwords (FIDO2)

This is the second option made available in Azure AD in July 2019. This allows the use of hardware tokens such as Windows Hello and FIDO2 devices (i.e. Yubikey and others) to authenticate to the platform. Note that this is not MFA – you have one factor, the hardware token. There is no requirement to implement a second factor with the hardware token as this replaces the password and is not storing a password. That is, if you do not have the token you do not have access – you cannot guess or intercept the token exchange.

To turn on this feature select the FIDO2 Security Key option under Authentication Methods (under Security) and then Authentication Method Policy (Preview).

As with the Microsoft Authenticator option above, Enable the feature and select All Users or Select Users.

Unlike the Microsoft Authenticator option, you now have the choice of Self Service and Key Restrictions

Self Service is useful when you have All Users selected, as the user registers their own security key. Without Self Service you need to configure a key for each user. Self Service requires the new registration service which is mentioned above and linked to at the top of the configuration page in Azure AD portal.

Enforce Attestation allows you to ensure that a specific model / device of hardware security key is used. Enforce Key Restrictions requires that you add the key by its AAGUID as shown:

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From here you can also Restrict Specific Keys to only allow keys you have issued to be used. Block would allow you to have any key.

Enhanced Registration Preview

This preview has been available since early 2019, but now supports passwordless and security token as authentication methods. Click the link in the blue bar and ensure everyone whom you have enabled the new authentication policy for is included for the new registration preview. In the graphic below, this is the lower of the two options – your tenant might show only the lower option.

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To direct users to the new preview experience visit http://aka.ms/mfasetup or if you have a Conditional Access login but you have not registered, you will be directed here anyway.

On the security info page, if you have already registered for MFA you will be shown your current authentication methods:

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If you have not registered before you will be asked to register – either way, you get to pick the methods you want to use for authentication. These need to be:

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  • Authenticator App – you can add up to five of these
  • Security Key

To add a new Security Key select this and follow the steps but make sure you are running Microsoft Edge on Windows 10 1903 or later or Firefox. On Chrome (which supports FIDO2 for Google Services) you get the below:

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On a supported browser, you will see the following series of prompts:

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The above is for a USB key. NFC keys and readers will have different prompts along the lines of holding the device near to the reader.

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Then you need to name your key:

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Signing In With A Security Key

Login to Office or your selected cloud app and enter your username and click next.

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Now you can click “Sign in with Windows Hello or a security key”

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As with registration, you now need to enter your PIN and press the button on the USB device, scan your fingerprint, look at your camera or hold your NFC device next to the reader – whatever your device requires you to do.

On your MFA registration page at https://aka.ms/mfasetup your security device is listed:

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Your login did not require a password – yippee!

Improving Password Security In the Cloud and On-Premises

Posted on 1 CommentPosted in active directory, Azure Active Directory, Azure AD, AzureAD, EM+S, enterprise mobility + security, microsoft, Office 365, password, security

Passwords are well known to be generally insecure the way users create them. They don’t like “complex” passwords such as p9Y8Li!uk%al and so if they are forced to create a “complex” password due to a policy in say Active Directory, or because their password has expired and they need to generate a new one, they will go for something that is easy to remember and matches the “complexity” rules required by their IT department. This means users will go for passwords such as WorldCup2018! and Summ3r!!. Both these exceed 8 characters, both have mixed case, both have symbols and numbers – so both are complex passwords. Except they are not – they are easy to guess. For example, you can tell the date of this blog post from my suggestions! Users will not tend to pick passwords that are really random and malicious actors know this. So current password guidance from NIST and UK National Cyber Security Centre is to have non-expiring unknown, not simple passwords that are changed on compromise. Non-expiring allows the user to remember it if they need to (though a password manager is better) and as it is unknown beforehand (or unique) means its not on any existing password guess list that might exist.

So how can we ensure that users will choose these passwords! One is end user training, but another just released feature in the Microsoft Cloud is to block common passwords and password lists. This feature is called Azure AD Password Protection. With the password management settings in Azure AD, cloud accounts have been blocked from common passwords for a while (passwords that Microsoft see being used to attempt non-owner access on accounts) but with the password authentication restrictions you can link this to block lists and implement it with password changes that happen on domain controllers.

So how does all this work, and what sort of changes can I expect with my passwords.

Well what to expect can look like this:

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Note all the below is what I currently know Microsoft do. This is based on info made public in November 2018 and documented at https://docs.microsoft.com/en-us/azure/active-directory/authentication/concept-password-ban-bad and is subject to change as Microsoft’s security graph and machine learning determines change is needed to keep accounts secure.

Password Scoring

First, each password is scored when changed or set by an administrator or a user on first use. A password with a score less than 5 is not allowed. For example:

spring2018 = [spring] + [2018] = 2 points

spring2018asdfj236 = [spring] + [2018] + [asdf] + [f] + [j] + [2] + [3] + [6] = 8 points

This shows that common phrases (like Spring and 2018) can be allowed as part of password that also contains stuff that is hard to guess. In this, the asdf pattern is something straight from a Qwerty keyboard and so gets a low score. In addition to the score needing to exceed 5, other complexity rules such as certain characters and length are still required if you enforce those options. Passwords are also “normalized”, which lower cases them and compares them in lower case – so spRinG2018 is as weak as spring2018. Normalization also does common character replacesments such as $=s, so $PrinG2018 is the same as spring2018 and also just as weak!

You name is not allowed in any password you set and the logic applies to an edit distance of 1 character – that is if “spring” is a blocked word then “sprinh” would also be blocked, h being one character away from g.

Common and Blocked Lists

Microsoft provide the common password lists, and these change as Microsoft see different passwords getting used in account attacks. You provide a custom blocked list. This can contain up to 1000 words, and Microsoft apply fuzzy logic to yours and the common list. For example we added all our office locations as shown:

image

This means that both capetown and C@p3t0wn would be blocked. The @=a, the 3=e and the 0=o. So the more complex one is really not complex at all as it contains common replacements.

In terms of licences, the banned password list that Microsoft provides is licence free to all cloud accounts. You need AAD Basic if you want to add your own custom banned password list. For accounts in Windows Server Active Directory you need the Azure AD Premium (P1) licence for all synced users to allow downloading of the banned password list as well as customising it with your words so that Active Directory can apply it to all users on-premises to block bad passwords (even those users not synced to AzureAD).

Hybrid Password Change Events Protected

The checks on whether a password change should be stopped is included in hybrid scenarios using self-service password reset, password hash sync, and pass-through authentication, though changes to the custom banned password list may take a few hours to be applied to the list that is downloaded to your domain controllers.

On-Premises Changes

There is an agent that is installed on the domain controllers. Password changes are passed to the agent and it checks the password against the common list and your blocked list. The agent does the password check, and it checks it against the most recently downloaded list from Azure AD. The password for on-premises is not passed up to Azure AD, the list is downloaded from Azure AD and processed locally on the domain controller. This download is done by the Azure AD password protection proxy. The list is then downloaded once per hour per AD site to include the latest changes. If your Azure AD password protection proxy fails, then you just use the last list that was successfully downloaded. Password changes are still allowed even if you lose internet access.

Note that the Azure AD password protection proxy is not the same as the Pass-Through Authentication agent or the AAD Connect Health agent. The Azure AD password protection proxy can though be installed on the same servers as the PTA or Connect Health agent. Provisioning new servers for the proxy download service are not required.

The Azure AD password protection proxy wakes up hourly, checks SYSVOL to see the timestamp of the most recently downloaded copy and decides if a new copy is needed. Therefore if your intra-site replication is within the hour, proxy agents in other sites might not need to download the list as the latest is already available via DFSR between the domain controllers.

The Azure AD password protection proxy does not need to run on a domain controller, so your domain controllers do not need internet access to obtain the latest list. The Azure AD password protection proxy downloads the list and places it in SYSVOL so that DFSR replication can take it to the domain controller that needs it.

Getting Started

To set a custom password block list, in the Azure Portal visit the Azure AD page, click Security and then click Authentication Methods (in the Manage section). Enter your banned passwords, lower case will do as Microsoft apply fuzzy logic as described above to match your list to similar other values. Your list should include common words to your organization, such as location, office address keywords, functions and features of what the company does etc.

For Active Directory, download the agent (from the Microsoft Download Center) to one or more servers (for fault tolerance). These will download the latest list and place it in SYSVOL so that the domain controllers can process it. Two servers in two sites would probably ensure one of them is always able to download the latest copy of the list.

The documentation is found at https://aka.ms/deploypasswordprotection.

Microsoft suggests that any deployment start in audit mode. Audit mode is the default initial setting where passwords can continue to be set even if they would be blocked. Those that would fail in Enforce mode are allowed in Audit mode, but when in audit mode entries in the event log record the fact that the password would fail if enforce was turned on. Once proxy server(s) and DC agents are fully deployed in audit mode, regular monitoring should be done in order to determine what impact password policy enforcement would have on users and the environment if the policy was enforced.

This audit mode allows you to update in-house policy, extend training programs and offer password advice and see what users are doing that would be considered weak. Once you are happy that users are able to respond to an password change error because the password is too weak, move to enforce mode. Enforce mode should kick in within a few hours of you changing it in the cloud.

Installing the Proxy and DC Agent

Domain Controllers need to be running Windows Server 2012 and later, though there are no requirements for specific domain or forest functional levels. The Proxy software needs to run on a Windows Server 2012 R2 or later server and be running .NET 4.6.2 or later. Visit the Microsoft Download Center to download both the agent and the password protection proxy. The proxy is installed and then configured on a few (two at most during preview) servers in a forest. The agent is installed on all domain controllers as password changes can be enacted on any of them.

To install the agent, run AzureADPasswordProtectionProxy.msi on the server that has internet connectivity to Azure AD. This could be your domain controller, but it would need internet access to do this.

To configure the agent, you need to run once Import-Module AzureADPasswordProtection followed by Register-AzureADPasswordProtectionProxy and then once the proxy is registered, register the forest as well with Register-AzureADPasswordProtectionForest all from an administrative PowerShell session (enterprise admin and global admin roles required). Registering the server adds information to the Active Directory domain partition about the server and port the proxy servers can be found at and registering the forest settings ensure that information about the service is stored in the configuration partition.

Import-Module AzureADPasswordProtection
Get-Service AzureADPasswordProtectionProxy | FL
$tenantAdminCreds = Get-Credential
Register-AzureADPasswordProtectionProxy -AzureCredential $tenantAdminCreds
Register-AzureADPasswordProtectionForest -AzureCredential $tenantAdminCreds

If you get an error that reads “InvalidOperation: (:) [Register-AzureADPasswordProtectionProxy], AggregateException” then this is because your AzureAD requires MFA for device join. The proxy did not support MFA for device join during the early preview but that should now be resolved – make sure you are using the latest download of the agent and proxy code. you need to disable this setting in Azure AD for the period covering the time you make these changes – you can turn it back on again (as on is recommended) once you are finished configuring your proxy servers. This setting, should you need to disable it, is found at:

  • Navigate to Azure Active Directory -> Devices -> Device settings
  • Set “Require Multi-Factor Auth to join devices” to “No”
  • As shown
    image
  • Then once the registration of your two proxies is complete, reverse this change and turn it back on again.

Once at least one proxy is installed, you can install the agent on your domain controllers. This is the AzureADPasswordProtectionDCAgent.msi and once installed requires a restart of the server to take its role within the password change process.

The PowerShell cmdlet Get-AzureADPasswordProtectionDCAgent will report the state of the DCAgent and the date/time stamp of the last downloaded password block list that the agent knows about.

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Changes In Forest

Once the domain controller the agent is installed on is rebooted, it comes back online, finds the server(s) running the proxy application and asks it to download the latest password block list. The proxy downloads this to C:\Windows\SYSVOL\domain\AzureADPasswordProtection. Older versions of the proxy and agent used a folder called
{4A9AB66B-4365-4C2A-996C-58ED9927332D} under Policies folder. These versions of the agent stop working in July 2019 and need to be updated to the latest release.

In the Configuration partition at CN=Azure AD Password Protection,CN=Services,CN=Configuration,DC=domain,DC=com some settings about the service are persisted. If the domain controller has the agent installed then

CN=AzureADConnectPasswordPolicyDCAgent,CN=<DomainControllerName>,OU=Domain Controllers,DC=domain,DC=com is created.

And then on each domain controller, in the Event Viewer, you get Application and Services Logs > Microsoft > AzureADPasswordProxy with DCAgent on the DC’s and ProxyService on the proxy servers. The EventID’s are documented at https://docs.microsoft.com/en-us/azure/active-directory/authentication/howto-password-ban-bad-on-premises-monitor.

The monitoring Event ID will cover things like user password change differently than admin password set. This allows you to audit who (end user or service desk) is setting weak passwords.

Once the proxy starts to work, the above folder starts to get content. In my case in the preview it took over 2 hours from installing the proxy as well as the documented installation and configuration PowerShell cmdlets listed above to get the proxy to download anything. The above listed Configuration folder contained some cfge files and the above listed PasswordPolicies contains what I assume is the downloaded password block list, compressed as its only 12KB. This is the .ppe file and there is one of these per hour downloaded. Older versions of this download are deleted by the proxy service automatically.

Audit Mode

Using the above Event ID’s you can track the users who have changed to weak passwords (in that they are on your or Microsoft’s banned password list) when the user or admin sets (or resets) the users password. Audit mode does not stop the user choosing the password that would “normally have been rejected” but will record different Event IDs depending upon the activity and which block list it would have failed against. Event id DCAgent/30009 for example has the message “The reset password for the specified user would normally have been rejected because it matches at least one of the tokens present in the Microsoft global banned password list of the current Azure password policy. The current Azure password policy is configured for audit-only mode so the password was accepted.”. This message is a failure against Microsoft’s list on password set. The user doing a password change and the Microsoft list gets DCAgent/30010 Event ID recorded instead.

Using these two Event ID’s along with DCAgent/30007 (logged when password set but fails your custom list) and or DCAgent/30008 (password changed, fails your custom list) allows you to audit the impact of the new policy before you enforce it.

Enforce Mode

This mode ensures that password set or change events cannot have passwords that would fail the list policies. This is enabled in the password policy in Azure AD as shown:

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Once this is enabled it takes a few hours to be picked up by the proxy servers and then for the agent to start rejecting banned passwords.

When a user changes their password in enforce mode they get the following error (different graphic depending upon Windows versions). If the admin changing the password uses a blocked password then they see the left hand graphic as well (Active Directory Users and Computers).

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or

This is no different to the old error you get when your password complexity, length or history is not met. Therefore there is no indication to the user that the password they chose might be banned rather than not allowed for the given reasons. So though password policy with a banned list is an excellent step forward, there needs to be help desk and end user awareness and communications (even if they are just a simple notification) as the user would not be able to tell from the client error they get. Maybe Microsoft have plans to update the client error?

Password changes that fail once enforce mode is enabled get Event ID’s such as DCAgent/30002, DCAgent/30003, DCAgent/30004 and DCAgent/30005 depending upon which password list the fail happened against and the method of password set or change. For example when I used the password Oxford123, as “oxford” is in the custom banned password list, Event ID 30003 returns “The reset password for the specified user was rejected because it matched at least one of the tokens present in the per-tenant banned password list of the current Azure password policy”. As mentioned above, the sequence of 123 following the banned word is not enough to make to score more than 5 points and so the password change is rejected.

On the other hand, 0xf0rdEng1and! was allowed as England was not on my banned list an so although my new password contained a banned word, there were enough other components of the password to make it secure enough. Based on the above mentioned scoring of 5 or more is required to have a password accepted, [Oxford] + [E] + [n] + [g] + [1] + [a] + [n] + [d] + [!], a total of 9. 9 >= 5 and so the password is accepted.

Finally, when testing users, other password policies like the date that the password can next be changed and “user cannot change password” property etc. will take effect over the banned password list. For example, if you have a cannot change password for 5 days setting, and you set the users password as an administrator – that will work or fail based on the password you enter, but if you change the password as the user within that time period, that will fail as five days have not gone by and not because the user picked a guessable password.

Password Writeback Errors

Posted on 9 CommentsPosted in Azure, Azure Active Directory, Group Policy, IAmMEC, Office 365, password

I had been struggling with password writeback testing and was coming across the following set of errors, and found that searching for them uncovered nothing online. So I wrote this blog to remind me and help you solve these issues. These errors are all visible in the Application log of the Event Viewer.

User Restrictions

The following error is because the user has “user cannot change password” option set in Active Directory:

EventID 33004: TrackingId: 7344da2c-ab9d-42ef-adea-4a17d07fdeb9, Reason: Synchronization Engine returned an error hr=80230626, message=The password could not be updated because the management agent credentials were denied access., Context: cloudAnchor: User_9b83f544-ba22-4ffb-bff5-c1c2374d654c, SourceAnchorValue: F39SWQrM2EidaboN8UC8Ww==, UserPrincipalName: ethan@contoso.co.uk, Details: Microsoft.CredentialManagement.OnPremisesPasswordReset.Shared.PasswordResetException: Synchronization Engine returned an error hr=80230626, message=The password could not be updated because the management agent credentials were denied access.
   at AADPasswordReset.SynchronizationEngineManagedHandle.ThrowSyncEngineError(Int32 hr)
   at AADPasswordReset.SynchronizationEngineManagedHandle.ChangePassword(String cloudAnchor, String sourceAnchor, String oldPassword, String newPassword)
   at Microsoft.CredentialManagement.OnPremisesPasswordReset.PasswordResetCredentialManager.ChangePassword(String encryptedChangePasswordRequestString, String publicKeyEncryptedSymmetricKey, String publicKeyEncryptedSymmetricIV)

And also, as the second error generated:

Event ID 6329: An unexpected error has occurred during a password set operation.
“BAIL: MMS(5716): ..\server.cpp(11139): 0x80230626 (The password could not be updated because the management agent credentials were denied access.)
Azure AD Sync 1.0.8641.0″

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Group Policy Restrictions

Its possible that the errors you see for password writeback in the application log are due to restrictions on the user’s password that they have chosen. If the password is not complex enough then you get a warning in the password reset page the user is visiting in Azure, but you can also get this is a Group Policy restriction is in place even if you have set a strong password. The text in the error message in the Azure password change portal reads “This password does not meet your corporate password policy. Please make sure to use a mix of upper and lowercase letters, numbers, symbols, and to update your password to one that you haven’t used previously.”. Therefore though Azure accepted the passwords (original and new) the on-premises server rejected them with the following:

Event ID 33008: TrackingId: 3c8c78dc-9167-4286-9384-e2f0e777af87, Reason: Synchronization Engine returned an error hr=80230619, message=A restriction prevents the password from being changed to the current one specified., Context: cloudAnchor: User_9b83f544-ba22-4ffb-bff5-c1c2374d654c, SourceAnchorValue: F39SWQrM2EidaboN8UC8Ww==, UserPrincipalName: ethan@contoso.co.uk, Details: Microsoft.CredentialManagement.OnPremisesPasswordReset.Shared.PasswordResetException: Synchronization Engine returned an error hr=80230619, message=A restriction prevents the password from being changed to the current one specified.
   at AADPasswordReset.SynchronizationEngineManagedHandle.ThrowSyncEngineError(Int32 hr)
   at AADPasswordReset.SynchronizationEngineManagedHandle.ChangePassword(String cloudAnchor, String sourceAnchor, String oldPassword, String newPassword)
   at Microsoft.CredentialManagement.OnPremisesPasswordReset.PasswordResetCredentialManager.ChangePassword(String encryptedChangePasswordRequestString, String publicKeyEncryptedSymmetricKey, String publicKeyEncryptedSymmetricIV)

and

Event ID 6329: An unexpected error has occurred during a password set operation.
“BAIL: MMS(5236): ..\server.cpp(11139): 0x80230619 (A restriction prevents the password from being changed to the current one specified.)
Azure AD Sync 1.0.8641.0″

This of course seems self explanatory – your password is not complex enough for your rules on-premises but complex enough to get past the Azure initial checks that it imposes.

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This error though is especially annoying in test scenarios where you have turned off all the complexity checks. To test why you are getting this error, first check its a password change error and not something else, and try and change the users password on-premises. You should get the same restriction. Then use the cmd prompt to check the password settings for the user.

</p> <p>net user username /domain</p> <p>

This will report the following:

User name                    user1
Full Name                    First Last
Comment
User’s comment
Country/region code          000 (System Default)
Account active               Yes
Account expires              Never

Password last set            7/7/2015 3:19:00 PM
Password expires             Never
Password changeable          7/8/2015 3:19:00 PM
Password required            Yes
User may change password     Yes

Workstations allowed         All
Logon script
User profile
Home directory
Last logon                   7/8/2015 10:31:05 AM

Logon hours allowed          All

Local Group Memberships
Global Group memberships     *Domain Users
The command completed successfully.

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In this example, notice the highlighted. Here there password minimum age requirement in Group Policy has been removed:

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But the domain controller (after running gpupdate to force the change to the domain controller) still enforces a single day to allow the change to occur.

For test scenarios, modify group policy to 0 days (rather than not defined) and probably increase the max age from the suggested default of 30 days:

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After running gpupdate, you get the following for the net user command:

Password last set            7/8/2015 10:42:05 AM
Password expires             Never
Password changeable          7/8/2015 10:42:05 AM

Now you should be able to change your password in Azure against an on-premises user.

Strong Password Required

In the password change portal, the user is required to enter a strong password regardless of any restrictions that you have on-premises. So even if you are testing and have removed all history and complex and renewal requirements for the password, Azure will ensure that a strong password of 7 or more characters is entered regardless of your on-premises policy. In fact, Azure does not know your on-premises policy for password restrictions and enforces its own in addition to the one you have.

You get errors in the portal that read “Strong password required. Combine at least three of the following: uppercase letters, lowercase letters, numbers, and symbols.”. You also cannot reset the password to the same and the errors you get look like the following options:

image image image image 

Success

For completion of the blog, here is what you should see in the event log when it is working:

Event ID 31006: TrackingId: f430189d-984c-41d5-a4a6-333c66ffae1f, ChangePasswordRequestStart, Details: ethan@contosochemists.co.uk

Event ID 31007: TrackingId: f430189d-984c-41d5-a4a6-333c66ffae1f, ChangePasswordSuccess, Details: Context: cloudAnchor: User_9b83f544-ba22-4ffb-bff5-c1c2374d654c, SourceAnchorValue: F39SWQrM2EidaboN8UC8Ww==, UserPrincipalName: ethan@contosochemists.co.uk

Windows RRAS VPN and Multi Factor Authentication

Posted on 6 CommentsPosted in Azure, MFA, multi-factor auth, password, phone factor, policy, pptp, remote desktop, rras, sdk, vpn

This blog post covers the steps to add Multi Factor Authentication (MFA) to Windows RRAS server. Once this is enabled, and you sign in with a user enabled for MFA in Azure Multi-Factor Authentication Server (an on-premises server) you are required to answer your phone before you can connect over the VPN. That is, you connect to the VPN endpoint, enter your username and password and if they are correct, then confirm that you want to authenticate by answering your phone. If you are not connecting over VPN and someone else is and using your credentials, unless they also have your phone they are not going to succeed! And all this for less than a £1 per user per month!

This configuration requires the following components set up:

  • Multi Factor Authentication set up in Azure
  • Azure Multi-Factor Authentication Server installed on-premises
  • Some users configured in Azure Multi-Factor Authentication Server
  • RRAS VPN server configured to use RADIUS for authentication, with the MFA server being the RADIUS endpoint

Step 1: MFA setup in Microsoft Azure

To do this you need an Azure subscription and DirSync configured to populate the Azure Active Directory with users. If you already have Office 365 with DirSync then you have this configuration already and you can login to Azure using the Azure AD link from the Office 365 management portal.

Once in Azure select “Active Directory” from the portal and click “Multi-Factor Auth Providers” from the menu at the top. You will probably not have any providers listed here, but if you do already (for example you are already using MFA for Office 365 or AD FS) then you can use the existing provider. To add a provider click Add, select “Multi-Factor Auth Provider” and “Quick Create” as shown:

image

Provide a name and then choose a usage model. Usage models are per user or per authentication. Per User works when a single user will authenticate more than 10 times a month. When users would only use MFA occasionally you can buy the service by the authentication request. For example if you had 200 VPN users who connected each day, you would choose Per User. But if you had 200 VPN users, who only dialled in once a month (i.e. a total of 200 authentications) then you would be better off buying the Per Authentication model as you would pay for 20 batches of authentications (each batch allows 10 authentications regardless of the user). You cannot change the authentication model without removing the auth provider and making a new one.

Finally, link the provider to your directory.

Select your auth provider once it is created and click Manage at the bottom of the portal:

image

This opens a new tab in the browser and takes you to the Azure Multi-Factor Authentication management pages.

Whilst here, as there is actually not a lot to do here, take a look at Configure to see what settings you can change. Maybe enter your email address for the fraud alert notifications, but leave everything else as is for now.

Back on the home page of the Azure Multi-Factor Authentication web site, click Downloads.

Step 2: Installing Multi-Factor Authentication Server

From the Downloads page find the small download link (above the Generate Activation Credentials button) and download the software to a Windows Server that is joined to your domain.

On the said server install .NET 2.0 and IIS with the default settings. Ensure that you have a digital certificate installed, as the web site the the users will go to for provisioning and managing their device is available over SSL. Mobile phones can use the app to validate connections as well, and that will be the subject of a different blog post, but you need a trusted cert that is valid and has a subject name such as mfa.domain.com (where domain.com is your domain) and so a 3rd party cert is required. In this blog I have used my wildcard cert from DigiCert.

Run the Multi-Factor Authentication Server installer and proceed through the steps. Use the wizard to configure the server and select VPN. During the installation you will also need to authenticate the Multi-Factor Authentication Server to Azure. This requires a set of credentials that are valid for ten minutes at a time, and generated from the Generate Activation Credentials button in the management web page at Azure. So don’t click this button until the Multi-Factor Authentication Server requires this info.

For this blog I am going to protect my VPN with Azure MFA. Therefore during the configuration wizard I select just the VPN option:

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As you proceed through the wizard you will be asked about the RADIUS client configuration needed for your VPN provider. In here enter the IP address of your RRAS box and a password that you have made up for the occasion. You will need this password, or shared secret, when configuring the RRAS server later.

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Finish the installation of Multi-Factor Authentication Server.

Once complete, open the Multi-Factor Authentication Server management program and select RADIUS Authentication. Ensure Enable RADIUS authentication is selected as this will allow this server to provide authentication on behalf of the RADIUS client and therefore insert requests for MFA via the users phone into the authentication flow.

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Double click the IP address of your VPN server and select “Require User Match”

Step 3: Configure Users for MFA

Click the Users icon in Multi-Factor Authentication Server and click Import from Active Directory. Set the filtering to add just the users you want to enable MFA for. A user who dials in who is not listed here will not be blocked from authentication to the VPN.

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A user will have a yellow warning icon next to it if it is disabled. For disabled users you can either allow authentication to pass through the MFA server without requiring the user to have the second factor of authentication working. This can be set on the users properties, and the Advanced tab by selecting Succeed Authentication for “When user is disabled”. The enabled check box is on the general tab.

If a user is enabled here then they will need to either complete the MFA authentication process. The exact process the user needs to do to pass the authentication process always starts with getting their username and password correct. After that they can do one of the following:

  • Press # when the call comes through to their phone
  • Reply to a text message – texts go to a US number, so this might cost the user international rates!
  • Press the Verify button on the MFA app on their phone
  • Optionally add a PIN number to any of the above – for example, when the MFA call comes through to enter your PIN and then press # rather than just #.

Each user can have different settings. When you import users from the Active Directory it reads (by default) their mobile number from the Active Directory as the primary number to authenticate against. You can set backup numbers if required. If a user has a mobile number they are enabled by default. When importing you can set which MFA method the user will use, and you can install the MFA portal so the user can change their own settings if you want (outside the scope of this blog).

By now you have Azure MFA configured, the MFA server installed on-premises (it will need port 443 access to Azure to complete the authentication) and users set up in the MFA server. The MFA server is also configured to act as a RADIUS endpoint for your VPN service. If you install more than one MFA server for load balancing and HA, ensure that each MFA server is selected on the Multi-Factor Auth Servers tab on the RADIUS settings – this starts the MFA RADIUS service on each selected machine.

Before you configure VPN, final step here is to test the user. From the Users area on the MFA server select a user and click Test. Authenticate as the user, username and password required for this test, and then press # after answering the phone. Try out the SMS or text message form factor for authentication as well. To support the mobile app you need to install the users portal, the SDK and the mobile app web service – so thats for a different blog post.

Step 4: Configure RRAS VPN to Use Multi-Factor Authentication

Finally, change to your RRAS server. Before going any further, ensure that RRAS is working before MFA is enabled – you don’t want to troubleshoot MFA only to find it was RRAS not working in the first place! The RRAS server’s IP address must match the IP address listed under the RADIUS configuration in the MFA server.

Right-click the RRAS server name in the Routing and Remote Access console. If you are setting up MFA for another type of VPN server then any that supports RADIUS will do. In the server properties, select the Security tab and change the Authentication provider to RADIUS Authentication (it was probably Windows Authentication).

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Click Configure to the right of this drop-down and click Add:

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Enter the IP address of your MFA server, repeating the Add process if you have more than one MFA server configured. Enter the shared secret that you used when setting up the MFA server and ensure that the timeout is set to 60 seconds. This is an important setting. When the user connects to the VPN server, the timeout needs to exceed the time it will take for the users phone to ring, listen the the greeting, enter the PIN (optionally) and press #. One minute should be enough to do this. After one minute the RRAS VPN server will automatically fail authentication, so the user has one minute to complete the second factor authentication on their phone.

You should now be able to dial into your VPN and authenticate with your username and password. Once you succeed with this, the MFA authentication starts and the call will arrive on your phone:

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You can get the graphic as a vCard from http://1drv.ms/1xXCA01. Download this vCard, save it to your contacts and when you sync your contacts to your phone, your phone will tell you the Microsoft Phone Auth service is calling. You could change the name and graphic to suit, just make sure the number matches the CallerID setting in Azure MFA.

Whilst you are waiting for the call the arrive, and before you accept the auth request, the VPN client appears to pause:

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Once you complete the auth, the VPN session starts up. If the call and time to answer exceeds 60 seconds, then consider increasing the RADIUS timeout on the VPN server.

Finally, and this will be a different blog post, you might want to offer the user a portal they can go to to change their settings such as updating phone number and changing mode of authentication etc. But this is off topic for this post. Later posts will cover using this MFA server integrated with AD FS and OWA as well.

Access Is Denied Message After Sysprep–How To Fix

Posted on 1 CommentPosted in 2003, 2007, 2008, 2008 R2, 2012, 64 bit, backup, bios, hyper-v, password, recovery, sysprep, windows, windows 2003, windows 2008, windows 7, windows server, workstation, x64, x86

If before you use Sysprep to prepare a Windows machine for imaging you set the administrators password “User cannot change password” then sysprep will not clear this setting, but will set the “User must change password at next logon” setting. Normally these two settings are mutually exclusive, but in the scenario for sysprep it seems they can both end up being set.

This means you get prompted to reset you password at first logon after sysprep completes and then find you have “Access Denied” as the response. There is seemingly no way around this Catch-22.

That is unless you use the Offline NT Password and Registry Editor. This tool allows password resets when booting the server from a CD or USB key (so physical access to the server is required). As the download for this is an iso file, it can also be used in virtual environments by configuring your virtual machine to boot from the iso you have downloaded.

To allow you to logon to your machine following the above issue, all you need to in the Offline NT Password tool is to blank out the administrators password and unlock the account. These are options 1 and 4 during the password reset stage. Full instructions with screenshots follow:

  1. Boot the server with the issue with the Offline NT Password and Registry Editor iso file:
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  2. Choose the correct boot option (or just press Enter for the defaults):
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  3. For Vista and earlier select the default of Option 1. For Windows 7 and Windows 2008 and later select Option 2 (to boot into the second partition on the disk). You might need to select a different option if you have more partitions. You need to select the partition that Windows is installed on.
  4. If the disk is marked as Read-Only ensure that the server went through a clean boot and was not shutdown incorrectly. Once the messages indicate a writable partition
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  5. Select the presented folder (by pressing Enter again). You can typically just press Enter through most of these stages. You will be asked what you want to do – we want to reset passwords:
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  6. Select Option 1 to Edit user data and passwords:
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  7. Press Enter to choose the Administrator account:
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  8. Type 1 to Clear (blank) user password. You should get back the message “Password cleared!”:
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  9. Press Enter again to reselect the Administrator account, and this time select Option 4 to unlock the account (even though this program tells you the account is already unlocked):
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  10. Once you see “Unlocked!” you can quit from this program. The process to quit requires you to save your changes. Note that the default setting is not to save changes, so you cannot now use Enter to select the default option.
  11. Enter ! to quit from the password reset program:
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  12. Enter q to quit from the script and to ask about saving changes:
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  13. Enter y to write back the files that have been changed:
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  14. You should have been told “***** EDIT COMPLETE *****”. Press Enter to finish the program scripts:
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  15. At this final screen you can remove the CD or unmount the iso image from your virtual machine and press CTRL+ALT+DEL to restart the server. The server should now boot into Windows and auto-logon as it has a blank password.
  16. Change the password and optionally untick the “User cannot change password” setting.

How to Clear Password Policy on workstation after removing it from domain

Posted on Leave a commentPosted in domain, password, policy, workstation, xp

I needed to set up a few machines for a client in an internet cafe type scenario, but the client provided me with computers that had been added to the domain. The domain had a password requirement which meant I could not configure the default login on the cafe machines to have no password.
To reset the domain policy without adding the computer back into the domain and actually changing the policy for a short while you can reset the security settings on an XP computer to that at install time using the following command:

 secedit /configure /cfg %windir%\repair\secsetup.inf /db secsetup.sdb /verbose

This resets lots of settings back to the default installation configuration, but meant that I did not need to reinstall the operating system.
For full details on the limitations of the above command see http://support.microsoft.com/default.aspx?scid=kb;en-us;313222