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On March 2, Microsoft released patches to address four zero-day vulnerabilities in Microsoft Exchange Server software. Those vulnerabilities, known collectively as ProxyLogon, affect on-premises Exchange Server 2013, Exchange Server 2016, and Exchange Server 2019. (Exchange Online, which is part of Microsoft 365, has not been affected.)
This Exchange Server attack is the kind of industry-wide security event that may have even broader implications than the SolarWinds attack. Reports indicated that cybercriminals were already able to breach more than 30,000 organizations due to this active exploitation, and the number of attempted attacks observed against vulnerable Exchange Servers increased by orders of magnitude. Roughly 125,000 Exchange servers might still be vulnerable.
If you read into the technical details published about the attacks, you observe that essentially an entire kill chain occurred, meaning there were multiple vulnerabilities in Exchange Servers and an attacker would need to exploit several, or all of them, to achieve a successful attack. The first of the vulnerabilities, a remote code execution exploit, is a network-based vulnerability, specifically refer