Emergency fix for Exchange Y2K Bug

BACKGROUND
 
Microsoft has released an emergency fix for a year 2022 bug that is breaking email delivery on on-premise Microsoft Exchange servers. Email is getting stuck in the queue, and these errors are caused by Microsoft Exchange checking the version of the FIP-FS antivirus scanning engine and attempting to store the date in a signed int32 variable.
The problem relates to a date check failure with the change of the new year and is not a failure of the AV engine itself. This is not an issue with malware scanning or the malware engine, and it is not a security-related issue.

IMPACT

  Failure & shuts down the organization's email
  Prevents Exchange servers from sending emails

SYSTEM AFFECTED
  Microsoft Exchange 2016
  Microsoft Exchange 2019

RECOMMENDATIONS
 
Microsoft has released a temporary fix requiring customer action while working on an update that automatically fixes the issue.
This fix comes in the form of a PowerShell script named 'Reset-ScanEngineVersion.ps1.' When executed, the script will stop the Microsoft Filtering Management and Microsoft Exchange Transport services, delete older AV engine files, download the new AV engine, and start the services again.

To use the automated script to apply the fix, you can follow these steps on each on-premise Microsoft Exchange server in your organization:
1.     Download the Reset-ScanEngineVersion.ps1 script from https://aka.ms/ResetScanEngineVersion
2.     Open an elevated Exchange Management Shell
3.     Change the execution policy for PowerShell scripts by running Set-ExecutionPolicy -ExecutionPolicy RemoteSigned
4.     Run the script
5.     If you had previously disabled the scanning engine, enable it again using the Enable-AntimalwareScanning.ps1 script.

Microsoft warns that this process may take some time, depending on the organization's size.

Microsoft has also provided steps that admins can use to update the scanning engine manually: https://techcommunity.microsoft.com/t5/exchange-team-blog/email-stuck-i…