Security

M365 Mail Security with DKIM and DMARC - Technical implementation and best practices

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Banner - M365 Mail Security with DKIM and DMARC

Forged sender addresses and domain-based spoofing attacks continue to be among the most effective attack vectors in email traffic. In the Microsoft 365 world, SPF, DKIM and DMARC are important and necessary building blocks for protecting sender domains, optimizing deliverability and making abuse transparent. However, consistent, technically sound implementation and ongoing operation are crucial. In this article, I will show you how to correctly implement DKIM and DMARC in Microsoft 365, what pitfalls there are and how to efficiently secure operations.

Easter Egg: User blocked during Easter - cause and solution

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Users being locked out

Over the Easter weekend of 2025, many organizations using Microsoft Entra ID (formerly Azure AD) were caught off guard when a significant number of users were suddenly blocked from accessing corporate resources. The cause? Entra ID categorized these accounts as “high risk” due to “leaked credentials”. Conditional Access Policies blocked these users from attempting access due to the existing risk. In this post, I'll explain what happened, why it happened, and most importantly, provide a simple and secure solution to the problem.

M365 Log-Size Calculation for Sentinel

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Sentinel Log-Size M365 Banner

Microsoft Sentinel is ideal for extending the functions of Microsoft Defender XDR and other Defender products. I have already explained this in more detail in the blog entry https://www.graber.cloud/microsoft-sentinel-for-microsoft-365-a-must-have/. But what does Microsoft Sentinel for Microsoft 365 actually cost? There is no clear answer to this question, which is due to the difficulty of calculating the M365 log size for Microsoft Sentinel. This blog deals with precisely this question. It is intended to serve as a guide for cost estimation and shed some light on the darkness of log size and Sentinel costs. M365 Log-Size Calculation for Sentinel - a guide to cost estimation.

Microsoft Sentinel for Microsoft 365 – a must have!

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Microsoft Sentinel is a cloud-native SIEM and SOAR solution. Microsoft 365 offers integrated security functions for Azure Active Directory (Entra), Microsoft Defender for Office 365, Microsoft Defender for Endpoint and Microsoft Cloud App Security. However, these features do not cover all possible attack vectors and vulnerabilities that hackers could exploit. In this blog post, I explore how Microsoft Sentinel extends the capabilities of Microsoft Defender XDR (and other Defender products).

Defender for Servers without Azure Arc

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Header for Blogpost "Defender for Cloud without Azure Arc

If you want to protect your servers from cyber threats, you may be relying on Defender for Servers from Microsoft, a leader in the Gartner Magic Quadrant. Microsoft has now announced the direct onboarding of Defender for Servers without Azure Arc and is now officially available. Direct onboarding is a new feature that allows you to add the servers you want to protect to Defender for Servers without needing Azure Arc for Servers. In this blog post, I'll explain what this means, the benefits of this option, and who can benefit from it. I will also compare the new option with Azure Arc for Servers.

Protecting AAD identities with the right MFA method

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It's no secret: cyberattacks are becoming more frequent and more sophisticated. But even the simplest techniques often lead the attackers to success. After all, the weakest link in the defense against cyber attacks is the human being. In this post, I show how you can protect Azure Active Directory (AAD) identities with the right MFA method without neglecting the human factor. Not only is the security aspect important to consider, but also user acceptance.

Azure Files and Kerberos Support - A Cloud Story

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AZ Files and Kerberos - Header

Back in 2021, Kerberos support for Azure AD was available as a preview. A lot has happened since then and the three-headed hellhound continues to make its way and shake up the cloud. This article is a collection of information on what Azure AD with Kerberos and Azure Files already provides and where the journey will go. This is because support for Azure Files with Kerberos has also recently been publicly communicated, although at the time of writing this article it is still in preview.

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