Damn Those Problems
15Mar/180

KB4088875 makes a new virtual network card!

Posted by TB

Another great update my Microsoft!

KB4088875, otherwise known as: "2018-03 Security Monthly Quality Rollup for Windows Server 2008 R2 for x64-based Systems (KB4088875)" (and other 2008R2/7 versions)

Click here to go to the KB article.

Update 19-03-2018:
BTW, when you decline the 4088875 one, make sure to also decline 4088878! As this one is part of the larger cumulative one, if you opt to decline one, also do the other.

Update 16-03-2018:
The update is reported to not be pushed anymore. It is available in the Windows Update Catalog, so at least you can install it on your own terms.

Also, specific issue has been added to the patch's known issues with the workaround of running a VBS script to copy the static IP settings from the old adapter to the newly created one.

The bug according to Microsoft:
"A new Ethernet virtual Network Interface Card (vNIC) may be created with default settings in place of the previously existing vNIC, causing network issues after applying this update. Any custom settings on the previous vNIC are still persisted in the registry but unused."

The issue
This one resets your static IP network settings back to DHCP.

While this is not a problem if you already use DHCP, use a newer Server OS or use DHCP reservations, otherwise it really sucks.

You win this lottery ticket by using a combination of Windows Server 2008 R2 with VMware ESXi. It seems the ESXi version doen't really matter.

Cause?
As per last update of this page, Microsoft still does not tell us the root cause of this issue causing people around to world to keep guessing.

I guess this is caused by the update causing VMware tools to go haywire and create a second virtual network adapter. You notice this when you enter the server's IP address into the new adapter. You get a notification that another adapter already has this IP, and if you want to remove this IP from the old one. (chose Yes)

The notification looks a lot like:
Same IP on adapter

Warning and/or important!
When you enter your server's IP adres into the new adapter, it looks like the default gateway is already set. This is not true! When you click OK and look again at the settings, the default gateway is empty... This is important because if your only way into that server is via RDP or something remote-connecting like that, you have a great chance of not getting in again. This happened to me one time on a virtual management server. I fixed this by installing the VMware integration services on another VM and opening the console that way. I may not have the perfect environment, but sharing is caring ๐Ÿ™‚

Note
There are reports of users using Windows 7 that are also impacted. This could very well be true because it shares the core code with 2008 R2. I guess it means Windows 7 on VMware, but I cannot say for sure because I never ran virtual Windows 7 machines with a static IP.

Aftermath
What to do after this issue?

There could be a second, ghosted network adapter left. You should remove this one to prevent other issues.
1: Open an administrative CMD window and enter: set devmgr_show_nonpresent_devices=1
2: Type: start devmgmt.msc to open your device Manager window
3: On the menu open View and click Show hidden devices
4: Expand Network adapters
5: Look for the 'old' network adapter and remove it. Do take care of removing the right one. You can find this by looking at a transparant icon.

Well, this is all for now. I hope it helped some of you guys! Do note that running Windows updates a few days after release is never a good idea, in my opinion. Always let someone else test it for you ๐Ÿ™‚

Interesting sources:
Also look at this Reddit for more/live info and guestimates by others admins: https://www.reddit.com/r/sysadmin/comments/84cw3n/kb4088875kb4088878_and_vmxnet3