The BSI warns of a massive global attack wave on VMware ESXi systems using the known vulnerability CVE-2021-21974. The vulnerability has been known since February 2021 and has been closed by a patch.
If you are running such a system, please read the attached document carefully and apply the patch immediately if necessary.
As an immediate measure, port 427 (SLP) on the external firewall has been closed. Please direct questions about this topic to: cert(at)uni-ulm.de