Over 80 percent of exposed Exchange servers are still vulnerable to a severe vulnerability. Microsoft Exchange vulnerability (CVE-2020-0688) exists in the control panel of Exchange, Microsoft s mail server and calendaring server. Researchers recently used Project Sonar, a scanning tool, to analyze internet-facing Exchange servers and sniff out which were vulnerable to the flaw. The flaw stems from the server failing to properly create unique keys at install time, opens servers up to attackers, who could execute code remotely on them with system privileges.
Source: https://threatpost.com/serious-exchange-flaw-still-plagues-350k-servers/154548/