Microsoft released several urgent security updates for Exchange Server based on cyber attacks believed to be from HAFNIUM and other groups starting March 2, 2021.    This includes Microsoft Exchange Server 2019, 2016, 2013 and 2010, but not Exchange Online.  Microsoft recommends installation of security updates and running tests to see if Exchange servers have already been compromised.

The U.S. Justice Department has also executed a court-authorized operation to copy and remove malicious web shells from hundreds of vulnerable computers in the United States in relation to this security issue.   The FBI will attempting to provide notice of the court-authorized operation to all owners or operators of these computers.