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New security updates for Exchange Server (All versions)

Frank Zöchling

Microsoft has released security updates for Exchange Server today. Specifically, these updates address the following vulnerabilities:

CVE-2019-0817 applies to all currently supported Exchange Server versions (including Exchange 2010). CVE-2019-0858 affects Exchange from version 2013.

Even if the vulnerability is "only" classified as "Important", the corresponding updates should be installed promptly. It will not be long before the corresponding exploits are published.

Here you will find the corresponding links to download the updates:

Here is an excerpt from the description of the vulnerability:

A spoofing vulnerability exists in Microsoft Exchange Server when Outlook Web Access (OWA) fails to properly handle web requests. An attacker who successfully exploited the vulnerability could perform script or content injection attacks, and attempt to trick the user into disclosing sensitive information. An attacker could also redirect the user to a malicious website that could spoof content or the vulnerability could be used as a pivot to chain an attack with other vulnerabilities in web services.

To exploit the vulnerability, an attacker could send a specially crafted email containing a malicious link to a user. An attacker could also use a chat client to social engineer a user into clicking the malicious link. However, in both examples the user must click the malicious link.

The security update addresses the vulnerability by correcting how OWA validates web requests.

Qulle: CVE-2019-0817 | Microsoft Exchange Spoofing Vulnerability and CVE-2019-0858 | Microsoft Exchange Spoofing Vulnerability

Note: At least for me, the links for Exchange 2010 and Exchange 2013 are still not quite reliable. After a few attempts, however, it worked.

The basic rule is: test updates before they are rolled out in production.

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