How to write or migrate sidHistory with Powershell (3)

In our large scale Active Directory Cross Forest migration project, we now have migrated already 40.000 user accounts globally. Our self made scripting routine to migrate/write sidHistory into the target accounts turned out to be a robust, reliable part of the process and I feel safe now to share some experiences. We are running it on multiple migration servers around the globe as scheduled task – which you can easily call a “service” as it is running every 5 minutes.
I will write about the whole mechanism of how we automated our large scale Active Directory migration in another blog post, but will concentrate here to share our way of managing the sidHistory part.
As you know already from part 2 of this blog post, we were buidling our code on the examples that MSFT Jiri Formacek published here.

However, 2 main restrictions prevented us from using this code as is:

  1. We wanted to make sure that we really used the Domain Controller with the PDC Emulator role from source domain. Our source environment has 100+ domain controllers and the PDC role is siwtched from one DC to another DC under certain conditions. Therefore to use a fixed name for the PDC role Domain Controller was not acceptable.
  2. Our Active Directory account migration process was fully automated and it was the user who starts his/her migration not us. Therefore the requirement was given, that we only can run sidHistory migration (together with the account activation in target domain) as a continuous background service. Every session based approach would not have helped like we can find it in ADMT or Dell Migration Manager for Active Directory.
    Prepopulating sidHistory on the previously created disabled accounts in target domain was not an option, since Exchange 2010 was giving errors for disabled users with sidHistory of source active users under certain circumstances.

Solutions:
1) This was not a big thing. A small function could do the trick.

function getPDCE($domain) {
$context = new-object System.DirectoryServices.ActiveDirectory.DirectoryContext("domain",$domain)
$PDC=[System.DirectoryServices.ActiveDirectory.Domain]::GetDomain($context).PdcRoleOwner.Name
return $PDC
} 

2) This was not that easy (for us). Running our account migration script as usual – means as scheduled task with admin credentials – did not work for the sidHistory part in it since the credentials of the logged user account were not handed over to the SIDCloner routine.
All the code we could find on Jiri’s page asked for credential information interactively or would need explicit credentials in the script in another way.
Although we are packaging our Powershell Scripts into an .exe file by using Sapien Powershell Studio and could hide the password from simple file editing, putting user name and password into the script was not an acceptable way for us to go.
After testing back and forth, someone cam up with the idea of using the Windows credential manager to work around our deadlock situation.
The script would access the credential manager interface, get the credential information from there and would then pass them to the DsAddSidHistory function.
We created a function to retrieve credentials from Credential Manager store based on a very good script example to be found on Technet here.
While this seemed to be a clever way of achieving our target of having a scheduled user account activation script with sidHistory functionality, we ran into errors again. Retrieving credentials from Credential Manager by script obviously fails, when the script runs with exactly the credentials that you want to retrieve. This was true in our case, because the user account migration script was scheduled with that “big admin” account.

The solution finally was:
The user account migration script was running as a scheduled task with full admin credentials. When it came to migrate (in our project setup: activate) a user account in the target domain, it did not (could not) write sidHistory, but created an input file with username and target DC (the DC closest to the site where the user was had logged in from – remember that the user triggers his/her migration in our project).
On the same migration server a second script was scheduled with a server-local admin account. This script consists of 3 parts. First part is to check if there are new input files. Second part is to retrieve the full admin credentials from Credential manager and passing them to second part. Third part is to migrate sidHistory which succeeds because you have put all parts together for the SIDCloner routine:
PDC Emulator DC for source you have found by query.
Target DC was in file (but you can take every writable you want if replication delay does not matter).
Explicit credentials you get from Credential Manager.
Nowhere in both scripts password information is saved in clear text.

Additional Information

How to write (migrate) sidHistory with Powershell (1)

The adventure of sidHistory
I spent quite some hours during the last weeks to create a Powershell script routine that is able to “migrate sidHistory”. Migrate sidHistory in this context means to read the objectSID of a given user or group source object in Active Directory Forest A and write this value into the sidHistory attribute of a selected user or group object in Forest B.
Assuming there is a trust relationship between Forest A and Forest B and sidFiltering is disabled, user B from Forest B who has the sidHistory attribute filled with the SID of the user A from Forest A will have access to the same resources in Forest A like user A himself. The reason for this behavioris found in the fact that the security token of User B after successful logon will contain the SID of user A. From Windows’ token based access strategy, user B is now a user AB as long as we are talking about SID releated resource access.
From those few lines everyone agrees on the statememt that sidHistory functionality can be abused to get access to resources which are restricted for a user by default. In principle, you can add the SID of a given user from Forest A to any user in Forest B. There does not have to be a dedicated relationship like identical samaccountname of the two users (groups) etc. While exactly his functionality helps to ease Inter-Forest Active Directory migrations (and Intra Forest Migrations as well when you take care), it can also be a dangerous thread against your Active Directory security.
However, this not a new finding and Microsoft did well in treating sidHistory as a special attribute. It needs special treatment when you try to clear the values and it needs special treatment when you want to write values into it. I already published 2 posts about deleting sidHistory, see [Link], so we will concentrate here on writing sidHistory.

Writing sidHistory
The most common way in today’s Active Directory migration scenarios is writing sidHistory by using a migration software. Microsoft ships its own migration software called Active Directory Migration Tool (ADMT) which is capable of writing sidHistory. Other vendors like Dell Software’s Migration Manager for Active Directory (formerly known as Quest Migration Manager for Active Directory) provide a similiar functionality with a lot more options and the possibility to write sidHistory in an ongoing Active Directory Synchronization. Up to now Microsoft Forefront Identity Manager cannot help us here out of the box to fill this attribute as part of an Active Directory synchronization.
When you try to put a SID into the sidHistory attribute by using the standard Microsoft administrative tools like the attribute editor from ADUC, you will fail for sure.

errorsidhistory

You will also fail by using Powershell integrated LDAP based write operations for this attribute like set-aduser or set-qaduser.

errorsidHistory_a

We have to dig deeper here to reach our goal of Powershell based writing of sidHistory, which we will do in Part 2 of this blog post.

Dell Quest Migration Tools: Readiness for Windows Server 2012 and Exchange 2013

Actually we can see a good market response to the new Microsoft Server flagships, Windows Server 2012 and Exchange 2013.
Migration projects are still ahead and probably will not die in 2013.

The following table shows the readiness of the Quest migration tool suite  and answers the question whether the tool can be installed on a Windows Server 2012, whether it can migrate Active Directory to Windows 2012 and mail systems to Exchange 2013.

Microsoft did not release a new version of ADMT yet (the most actual version is still 3.2), that is fully compliant with Windows 2012 functional mode domains, nor can you install ADMT 3.2 on a Windows Server 2012 member server. Actually, a migration from a Windows 2008 R2 domain to a Windows 2012 domain with 2012 functional level can neither be achieved by using the native tool (ADMT) nor Quest Migration Manager for Active Directory.

Active Directory Product Version Tool installation on Windows Server 2012? Can backup/restore AD data on Windows Server 2012 DCs? OR Can migrate data to Windows 2012 DCs?
Recovery Manager for Active Directory Forest Edition 8.2.1 yes yes
Recovery Manager for Active Directory 8.2.1 yes yes
Migration Manager for Active Directory 8.9 No no
       
Migration Product Version Tool installation on Windows Server 2012? Can migrate data to Exchange 2013? Office 365?
Migration Manager for Exchange 8.9 no no/yes
Migration Manager for Exchange IntraOrg Edition 1.0.1 no yes
Notes Migrator for Exchange 4.6.1 no (no Windows 8 admin workstation) yes/yes
Coexistence Manager for Notes 3.4 no yes/yes
Groupwise Migrator for Exchange 4.2 no (no Windows 8 admin workstation) yes/yes