Security Updates for Microsoft Exchange Server (April 2021)

critical Nessus Plugin ID 148476
New! Plugin Severity Now Using CVSS v3

The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.

Synopsis

The Microsoft Exchange Server installed on the remote host is affected by multiple vulnerabilities.

Description

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)

Solution

Microsoft has released the following security updates to address this issue:
-KB5001779

See Also

http://www.nessus.org/u?3bdeeea7

http://www.nessus.org/u?b66291c9

Plugin Details

Severity: Critical

ID: 148476

File Name: smb_nt_ms21_apr_exchange.nasl

Version: 1.10

Type: local

Agent: windows

Published: 4/13/2021

Updated: 1/19/2022

Dependencies: ms_bulletin_checks_possible.nasl, microsoft_exchange_installed.nbin

Risk Information

CVSS Score Source: CVE-2021-34473

VPR

Risk Factor: Critical

Score: 9.8

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 8.7

Vector: AV:N/AC:L/Au:N/C:C/I:C/A:C

Temporal Vector: E:H/RL:OF/RC:C

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 9.4

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: E:H/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:microsoft:exchange_server

Required KB Items: SMB/MS_Bulletin_Checks/Possible

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/13/2021

Vulnerability Publication Date: 4/13/2021

Exploitable With

Metasploit (Microsoft Exchange ProxyShell RCE)

Reference Information

CVE: CVE-2021-28480, CVE-2021-28481, CVE-2021-28482, CVE-2021-28483, CVE-2021-33766, CVE-2021-34473, CVE-2021-34523

MSKB: 5001779

MSFT: MS21-5001779

IAVA: 2021-A-0160-S