https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34473

https://www.zerodayinitiative.com/advisories/ZDI-21-821/

http://packetstormsecurity.com/files/163895/Microsoft-Exchange-ProxyShell-Remote-Code-Execution.html

The Microsoft Exchange running on the remote host is affected by a remote code execution vulnerability. An unauthenticated remote attacker can exploit this to execute arbitrary code.

The Microsoft Exchange Server installed on the remote host is missing security updates. It is, therefore, affected by multiple vulnerabilities:

  - A remote code execution vulnerability. An attacker could exploit this to     execute unauthorized arbitrary code. (CVE-2021-28483, CVE-2021-28482,     CVE-2021-28481, CVE-2021-28480, CVE-2021-34473)

  - An elevation of privilege vulnerability. An attacker can exploit this to   gain elevated privileges. (CVE-2021-34523)

  - An information disclosure vulnerability. An attacker can exploit this to   disclose potentially sensitive information. (CVE-2021-33766)

ID	Name	Product	Family	Severity
152458	Microsoft Exchange Server RCE (ProxyShell)	Nessus	Windows	critical
148476	Security Updates for Microsoft Exchange Server (April 2021)	Nessus	Windows : Microsoft Bulletins	critical

CVE-2021-34473

critical

Tenable Plugins

critical

critical