Privilege escalation in Microsoft Exchange Server

1) Permissions, Privileges, and Access Controls

EUVDB-ID: #VU25227

Risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-0692

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The vulnerability allows a remote attacker to escalate privileges on the system.

The vulnerability exists due to uspecified error in Microsoft Exchange Server. Exploitation of this vulnerability requires Exchange Web Services (EWS) to be enabled and in use in an affected environment. A remote attacker can change parameters in the Security Access Token, forward it to a Microsoft Exchange Server and impersonate an another Exchange user. 

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 23 15.00.1497.002 - 2019 Cumulative Update 3 15.02.0464.005

External links

http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0692

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.