Moving Online? This Cloud Security Strategy Will Back Your Migration [part 1]

The decision has been made. Your organization is going to deploy Office 365. Let me tell you — cloud security is a SERIOUS game. I’m speaking from experience — and I want to share it with you, to make your life easier.

So here’s your detailed guide on what to do and what to avoid BEFORE moving to the cloud.

We’ll be talking about data quality and governance, its seamless synchronization and we’ll break down the perfect strategy on building your hybrid identity and authentication as well, and even more.

Let’s get started.

Where are we?

You are sitting at your desk, looking at the network diagram with all domain controllers, probably the Exchange servers and other services you’ve built over the years with your team.

Here comes the first question – where to start? What do we need to do?

The good news is you are not the first one to have such doubts eating you out. Even better news – I have helped plenty of our customers with securing their migration to the cloud, so I am ready to share some lessons learned from various projects.


Let’s then focus first on planning the steps to ensure your users with the best possible experience during this journey to the cloud. And let’s make it turbulence-free! The ultimate goal is to have your cloud services integrated and secure, right?

Insight #1: Technical details are important, but you can’t ignore the user experience in your plans. Ever heard about Amazon empty chair? Amazon CEO, Jeff Bezos was using it  during the meetings as a reminder to include customer view in their actions. You need an empty chair to represent your user when planning such a shift in your current IT. Usually, they don’t expect the change to happen, so great user experience and communication with the users might win their hearts.

Cloud security – one way or another?

In the first part of this puzzle, we’ll start with a typical case – imagine a company with an existing on-premise infrastructure based on Active Directory. Your users are logging on with AD credentials and then on-premise Exchange or another communication service.

Yes… whatever your perception might be, there are still other services around.  So far we have helped our clients to switch to Office 365 from their custom hosted mail systems,  Linux-based ones and Lotus Notes as well. At Predica we have moved from Google Apps to Office 365.

What my experience tells me is that most of the organizations will fall into this scenario, but the following ones may also be applicable:

A single organization with more advanced directory service structure (multiple domains within the single forest) – from the task perspective, it’s the same as with a single domain. A single organization with multiple AD forests or multiple organizations joining separate Office 365 services – this one might be a bit more challenging. Basic requirements to cover stay the same.  But how to get to these basics when multiple parts are moving? Here you may require some additional planning and dedicated experts help.

azure ad cloud security

Here’s how your identity synchronization in the cloud may look like in sequence of four steps.

To build your hybrid identity services for Office 365 you need to address three key elements:

  • Provide the right data from your directory
  • Establish the process of synchronization to keep it up to date between on-premise and cloud services
  • Select the way your users will authenticate their services (which directly influence their user experience). I’ll focus on that in the II part of this guideline.

Let’s handle this one by one.

The right data for your new and shiny directory tenant.

Did I write tenant? Is it a new word? Well – yes. And if you are not familiar with it, you will be as soon as you enter the realm of cloud services. The tenant is your instance of the directory in the cloud. That is where your user’s data and all the other Microsoft online services will reside.

So how to get the data from your tenant? Let’s try synchronizing  it with the existing Active Directory. How can you do this? By using Azure AD Connect (AAD Connect) tool provided by Microsoft.

Why this particular one? It is basically the most recent on the market – it will provide you with all the capabilities you need to synchronize your data.

  • AAD Connect supports synchronization of the data from multiple Active Directory forests and also from some other sources.
  • It also provides in-place upgrade and fail-over configuration. And this becomes critical when you start to use more advanced options provided by Azure AD, for instance, self-service password resets with a write-back).
AAD Connect supports synchronization of the data from multiple Active Directory forests

AAD Connect supports synchronization of the data from multiple Active Directory forests

Speaking of other tools, some of them you might have heard of earlier. Does any of these ring a bell?

  • DirSync – the oldest tool provided by Microsoft. In fact not needed anymore. Not an option for you right now.
  • AAD Sync – a DirSync replacement. Its support ends soon. More capable than DirSync but not providing all the options AAD Connect has to offer.
  • Microsoft Identity Manager (MIM) – MIM provides a connector for synchronization of data to Azure AD, but it is not supported anymore. Advanced data transformation and scenarios are also at stake, and it supports PowerShell as well. Practically, MIM is often used to support complex scenarios of data synchronization, even if the final push to the cloud is made with AAD Connect.

Here you can find a full comparison between these tools provided by Microsoft.

Insight #2: There might be only one AAD Connect instance synchronizing the data to a single tenant. At least this is a supported configuration. It means, if you have multiple data sources or directories in your organization, you need to consolidate them through single AAD Connect instance. It’s again for the complicated scenarios, e.g. synchronizing more than ten forests to single Azure AD. But it’s still doable.

What information is being synchronized to on-line Azure AD?

It depends on what services are used. Lists of attributes for each service are different, and it is well documented. However, based on my experience from current deployments, there is the special one causing most of the problems – userPrincipalName. Or simply saying – UPN.

cloud migration

What is UPN? It is a string attribute in your Active Directory, which allows the user to login with one’s full name, like, apart from what the user recognizes mostly as login name (which is technically samAccountName).

Why do you need to worry about it? Well, on-line service needs to know that the user belongs to your organization. Simple login name is not enough. Quick hint – there is more than one John in the world, I guess. So it requires something more consistent.

And the choice is the user’s e-mail address. When you synchronize the data from Active Directory to the on-line one, all the tools are assuming one thing – that your UPN contains exactly the value reliable to identify a user (based on its e-mail).

Why you actually don’t have to?  To be honest – almost no one cared about the format of UPN, and usually, it is in the default format of AD domain name, like john@predica.local (BTW – using “.local” as the domain name is a dreadful example. Why – this is the subject for another post). It’s not a big deal when most users didn’t even know it exists.

The good thing is that it’s easy to fix, here is what to do:

  • Get to know what is your planned e-mail domain(s) in Office 365
  • Verify that users have UPN values matching these domains. You can use Microsoft provided IdFix tool for it or custom PowerShell script.

You can learn more about the attributes synchronization and preparation while migrating them to the cloud services in Prepare to provision users through directory synchronization to Office 365 article from Microsoft.

There is no magic when it comes to directory data – garbage in, garbage out, that’s how it works.

And this is the moment when many of our clients are turning to Microsoft Identity Manager (MIM) to ensure, that information in the directory is being populated in the consistent and automated way. Especially since MIM synchronization service license is included in Windows Server – no additional cost attached.

microsoft identity management

But what if I can’t change my UPNs?

Are you doomed to fail? Is heaven falling? No. Take it easy – it just requires some more planning and additional work to do.

  • The first question is why you might not be able to change it? Usually, it comes down to those two reasons: There is one or more application assuming the UPN is a good identity handle, and it identifies users by that mean. It is a wrong assumption but let’s not go into this discussion here. From my experience and some past deployments, it might happen and stand for the blocking point. You need to check this before even considering to embrace any cloud services.
  • There is another trusted AD forest that is already using UPN suffix you also want to use.Less likely but still happens. Particularly in larger organizations. UPN suffixes are used for Kerberos authentication so in this case having the same two UPN suffixes might break a thing or two.

And here are the two possible remedies:

Insight #3: If you are changing the default configuration,  make sure you have them documented. AADConnectConfigDocumenter is open source tool which will make this task super easy. It’s good to document your configuration, even if it’s not a custom one. Same with backups – you don’t realize that you need them until you really need them.

And here you are – your users’ identities are in the cloud. The first step completed. At this point, you might start to ask a question how do you get into this tenant and how your users can log into it?

No worries, I’m going to let you rest by now. But hey! Come back soon for more clues, and now… go and test. And fix after testing. And ask me for help if needed.

In the second part of our hybrid identity set up guidance, we’ll work on the identity and authentication issues. So stay tuned!


If you have any questions, reflections or want to share a similar case study — the comment space below is aaaaall yours. (I’m telling you… you don’t even suspect how many people you’ll end up helping by simply typing your keys.)


See also

SharePoint Is Dead, Long Live SharePoint


Omada Enables Advanced Governance Control In Microsoft Azure


Crucial Questions To Ask Your Future SaaS Applications Provider


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