After we saw a rapid growth of Microsoft Office 365 users due to the lock down situation within the last 3 Month also Veeam Backup for Microsoft Office 365 gained more and more popularity.
In the background Microsoft announced some changes regarding the access security policy last year :
https://techcommunity.microsoft.com/t5/exchange-team-blog/basic-authentication-and-exchange-online-april-2020-update/ba-p/1275508
To improve security, the basic authentication method should be disabled in October 2020. Due to the additional challenging situation they decided to postpone the date to H2-2021.
As you know with higher security will come more complexity.
But if you have ever worked with Veeam I’m pretty sure you know that their priority in new features is always “it simply works”.
You can read through Polina’s blog how modern authentication works and what you need to configure (till Version 4b!):
https://www.veeam.com/blog/setup-multi-factor-authentication-office-365.html
https://www.veeam.com/veeam_modern_authentication_office_365_wpp.pdf
Version 4c ! OUT NOW !
I created a short “walk through” for you. Check out how easy it is to setup your application secret and ID with the new Veeam Backup for Microsoft Office 365 Version 4c (…in a Veeam usual way).
You can download the update here: https://www.veeam.com/kb3145
Lets start with adding the organization:

Select the organization deployment type (nothing changed here!) and click next.
Now you can choose the authentication method for your office 365 backup account:

You can still use legacy authentication which is necessary for some extended backup functionalities.
Let me Quote a line from Anton Gostevs Nwesletter “…But at least now our users have a choice between better security and richer functionality, instead of being forced into the latter”.
Don’t worry what happens after H2 2021 – I’m sure they will have a proper update for this case then!
(If you want to use legacy authentication please use Polinas blog for further setup)
We can then register a new Azure AD application completely automatically without switching to the Azure AD Portal!

Choose a proper name and click on “Install…” next to the certificate line:

In my case I was working with a self-signed certificate:

You will see the certificate string in the wizard after the self-signed process is finished:

Let’s allow the application to enable export mode to extend the restore functionalities and continue the wizard.
Now we need to connect our Office 365 account with the application. Copy the code and enter it at https://microsoft.com/devicelogin


Log in with your credentials and close the browser window after it was accepted.
HINT: If you want to create a separate backup account instead of using your global administrator you can find a complete guide here: https://www.veeam.com/kb2969

The wizard now shows that you are authenticated:

The organization will be added now and we have successfully installed the modern authentication.

Update 4c brings also a lot of other improvements to your environment like automatic updates, included hotfix pack with several solved issues and additional performance !
You can check out my colleagues blog with further informations: http://anthonyspiteri.net/backup-office-365-v4c-authentication/
To be honest – great improvements for a “feature update”.
Stay tuned for more