Microsoft Exchange Server Remote Code Execution Vulnerability
http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html
http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html
http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855