3DES/FIPS 140-2/RDP Hotfix

In the past I’ve written a blog about the issues my company encountered when we disabled 3DES on our Windows 2008 R2 systems. Since we are obligated to also use FIPS 140-2 for compliance reasons the combination of disabling 3DES, and having FIPS140-2 enabled would break remote desktop functionality. Basically it came down to RDP using hardcoded 3DES when FIPS140-2 was also enabled. Needless to say RDP would stop functioning when you disable the one thing it could use. When the sweet32 vulnerability came along we had to make a choice, do we want to be secure or do we want to be able to remotely connect? Unfortunately since disabling 3DES is a system wide setting it’s not possible to differentiate between protocols. Leaving us stuck in between a rock and a hard place. Last option was to file a case with Microsoft.

It took us several conversations with Microsoft support, providing evidence and creating a business case for the Windows product group to determine the potential impact. One of the challenges we faced was that Windows 2008 R2 has been out of mainstream support for a couple of years now. So any change on this level would require the product group to agree upon a design change, which is very rare in these kind of situations. After a few month’s they agreed and we eventually got a preview fix that worked like a charm!

As of today I’m glad to be able to announce that a permanent fix has been released. As it’s a platform fix, bound to the operating system it will be included in the Microsoft update cycle of next month. My Microsoft representative has promised that an individual KB will be released soon describing the specific issue and solution. I’ll update this post when it becomes available.

A current hotfix is already included in the preview for September 2017, which you can get here:
https://support.microsoft.com/en-us/help/4038803/windows-7-update-kb4038803

Or get it from the catalog:
http://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4038803

On a personal note, I would like to extend my gratitude to Microsoft support for the excellent push they did towards the product group convincing them on the necessity for this fix and working with me throughout this endeavor. My first experience being a customer instead of a Microsoft employee was a very pleasant experience!