Cloud PC (sold as the Windows 365 Product SKU) is the latest Virtual Desktop service hosted by Microsoft in Azure. This post (Part 1) documents some of the security concerns that Infosec Twitter has identified. Part 2 will explore ways to harden CloudPC/Windows 365.
Cloud PC (Announced 7/14/2021 and Generally Available 8/2/2021)
Azure Virtual Desktop (Announced 6/7/2021)
Windows Virtual Desktop (9/30/2019)
Azure RemoteApp (Retired on 8/31/2017)
Rand Morimoto wrote a nice write-up on Cloud PC (here), and the differences between it and Azure Virtual Desktop (here). Indeed, many have written articles on it, but the reason for this blog post is to examine the security and respond to some of the harsh criticism on Twitter (the InfoSec community on Twitter is probably the best ‘accountability’ buffer to keep Microsoft in check).
Most of what I have written about securing AVD/WVD (Part 1) and (Part 2) applies equally to Cloud PC. But what I love most about the business edition of Cloud PC is it eliminated all the overhead associated with spinning up the AVD/WVD environment (see Part 1 above to appreciate that effort). The Enterprise Edition requires some additional work but not as much as AVD/WVD, as explained in this Mechanics video here. There are already troubleshooting articles on the Hybrid Azure AD requirements here.
When I created my first Cloud PC, the provisioning process failed. I found out that there were issues with provisioning as described in the forums here. Turns out there were multiple issues and so I have published a separate blog post ‘Troubleshooting Windows 365 business’ here].
As an end user, you access your Cloud PC from: https://windows365.microsoft.com/
Also, it’s worth noting that on August 15th 2021, Microsoft is making Cloud PC available for end users to purchase on their own credit cards. IT Departments can disable this with PowerShell.
W365 Enterprise – update-MSCommerceProductPolicy -PolicyId AllowSelfServicePurchase -ProductId CFQ7TTC0HHS9 -Enabled $false
W365 Business/w Hybrid Benefits – update-MSCommerceProductPolicy -PolicyId AllowSelfServicePurchase -ProductId CFQ7TTC0J203 -Enabled $false
W365 Business – update-MSCommerceProductPolicy -PolicyId AllowSelfServicePurchase -ProductId CFQ7TTC0HX99 -Enabled $false”
Learn More: Use AllowSelfServicePurchase for the MSCommerce PowerShell module | Microsoft Docs
So why has Twitter been so unforgiving?
1. InfoSec Twitter does not like the default configuration of Local Administrator rights being given to the Cloud PC user. They claim this is not “secure by default.” It’s hard to argue with them on this point.
(1) Benjamin Delpy on Twitter: “Windows 365 is expensive and without basic security Did #mimikatz dumped my Azure *cleartext* password here? Or my Primary Refresh Token? It’s funny how you don’t apply best practices you recommend to the customer to avoid securing by default > https://t.co/Wzb5GAfWfd https://t.co/cMDq1a4l5e” / Twitter
It does appear Microsoft is exploring solving this according to this thread here:
Windows 365 Business Cloud PC Local Admin – Microsoft Tech Community
2. Mimikatz has been updated to dump Windows 365 credentials
(1) Benjamin Delpy on Twitter: “After a little bug report from @LawrenceAbrams, I just pushed a #mimikatz fix to dump even more #Windows365 credentials privilege::debug ts::logonpasswords > https://t.co/HjfZej6tqD” / Twitter
(1) Benjamin Delpy on Twitter: “Would you like to try to dump your #Windows365 Azure passwords in the Web Interface too? A new #mimikatz release is here to test! (Remote Desktop client still work, of course!) > https://t.co/Wzb5GAfWfd cc: @awakecoding @RyMangan https://t.co/hdRvVT9BtG” / Twitter
3. Lack of SecureBoot, UEFI, Credential Guard, etc
(1) Benjamin Delpy on Twitter: “Figure 1. VM with hardware enforced security, vTPM, SecureBoot, UEFI, Credential Guard, etc. Figure 2. #Windows365 without basic hardware security, no security feature, BIOS Guess the one running on an old ESXi in basement vs the new 365 revolution from Microsoft in #Azure ? https://t.co/PUGtqO0g3s” / Twitter