Exchange Server: New security updates (October 2022)

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Microsoft has released new security updates for all supported Exchange Server versions today. Microsoft explicitly points out that the updates do not contain a fix for the zero-day vulnerabilities (ProxyNotShell). The following vulnerabilities are fixed by the security update, three of the vulnerabilities are considered critical: CVE-2022-21979 CVE-2022-21980 CVE-2022-24477 CVE-2022-24516 CVE-2022-30134 The updates can be downloaded here: Exchange Server ... Read more

ProxyNotShell: Workaround can be easily bypassed

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The Exchange Mitigation EM1, which was published by Microsoft at the weekend, does not adequately seal the Exchange zero-day vulnerability ProxyNotShell (CVE-2022-41040) and can be easily bypassed. The problem is an "@" character in the Reg-Ex pattern, which makes the rule too precise. The Reg-Ex can thus be bypassed by making slight adjustments. This means that the rule is no longer ... Read more

Test: JAM Software Exchange Server Toolbox

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Many people will probably know JAM Software from the TreeSize tool, but JAM Software also has a product called "Exchange Server Toolbox" in its range. According to JAM Software, the Exchange Server Toolbox includes legally compliant and GDPR/GoBD-compliant email archiving, as well as a spam filter based on SpamAssassin, a virus scanner based on ClamAV and ... Read more

ProxyNotShell: Emergency Mitigation fixes zero-day vulnerability

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This weekend, Microsoft rolled out the URL rewrite rule, which prevents the successful attack via ProxyNotShell, as an emergency mitigation rule. This means that all Exchange 2016 and Exchange 2019 servers should be equipped with the workaround. However, this only applies if Exchange is at a current patch level and the emergency mitigation feature is active. For Exchange 2013 ... Read more

Detect Exchange Zero-Day Attack via PowerShell

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The Exchange Server zero-day vulnerability became known today and is already being actively exploited. A corresponding defense measure exists and should be implemented as quickly as possible. You can find out how the defense measure is implemented here: Exchange Server zero-day vulnerability is being actively exploited On the website of the company GTSC details about the currently ongoing attack were given, for this ... Read more

Exchange Server zero-day vulnerability is actively exploited

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A zero-day vulnerability in Exchange Server 2013, 2016 and 109 is currently being actively exploited. There is currently no security update for the following vulnerabilities: CVE-2022-41040 CVE-2022-41082 However, there is a workaround to avoid a successful attack. To prevent the vulnerability from being exploited, a rule can be created for the URL Rewrite feature. To do this, ... Read more

Implement Exchange Health Checker recommendations via script

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The Exchange Health Checker is an excellent tool to get a quick overview of the status of the Exchange Server. The PowerShell script provided by Microsoft is continuously updated and can generate a report in HTML format. For a fresh Exchange 2019 installation on a Windows Server 2022, the report looks like this, for example: ... Read more

MEC 2022: Session available on YouTube

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The "Microsoft Exchange Community (MEC)" conference was held from September 13 - 14, 2022. On these two days there were many sessions on Exchange on-Prem and Exchange Online. If you were unable to attend the free online conference, you can find the recordings of the sessions on Youtube: Microsoft Exchange Community (MEC) Technical Airlift - Sept 2022 Michel de Rooij also ... Read more

Exchange 2019: Configure anonymous relay

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Unfortunately, there are still applications or devices that can only send mails without authentication. This is not possible in the Exchange Server default setting. However, a new receive connector can be set up which allows anonymous relay for certain IP addresses. The following commands can be used on a server with an English-language operating system. Read more

Protect Exchange OWA with Duo 2FA

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Duo makes it very easy to protect OWA in an Exchange on-prem organization with 2-factor authentication. Duo is free for up to 10 users: https://duo.com/editions-and-pricing/duo-free Here is a short how-to for configuration. As soon as you have created a Duo account, you can search for "OWA" in the Admin Portal under "Protect an Application" ... Read more