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How to Use NsLookup To Check DKIM Record

Posted on by Rhoderick Milne [MSFT]
Check DMARC DNS Record Using NSLookUP

There are a multitude of online tools that help diagnose issues with various mail services, but understanding what these tools actually check is valuable.  One example is around manually checking published DomainKeys Identified Mail (DKIM) records.  DKIM is described in RFC 4871.  As an interesting piece of history DKIM went through a previous iteration "Domain-Based Email Authentication Using Pub… Read the rest “How to Use NsLookup To Check DKIM Record”

2

Exchange Server Extended Protection

Posted on by Rhoderick Milne [MSFT]
Exchange Server Extended Protection

Extended Protection uses service binding and channel binding to help prevent an authentication relay attack. In an authentication relay attack, a client that can perform NTLM authentication (for example, Windows Explorer, Microsoft Outlook, a .NET SqlClient application, etc.), connects to an attacker (for example, a malicious CIFS file server). The attacker uses the client's credentials to masquer… Read the rest “Exchange Server Extended Protection”

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Remediate Exchange Security CVE-2022-21978

Posted on by Rhoderick Milne [MSFT]
Remediate Exchange CVE-2022-21978

The May 2022 security update for Exchange Server 2013, 2016 and 2019 resolved CVE-2022-21978.  A common issue is that admins are only doing part of the work to address this CVE.  Yes they are installing the update, but are not reading the rest of the documentation which states that an additional command must be run.

The FAQ states:

Do I need to take further steps to be protected from this vulnerabil… Read the rest “Remediate Exchange Security CVE-2022-21978”

0

Migrate Safe Links Block Settings to TABL

Posted on by Rhoderick Milne [MSFT]
Migration of MDO Global Block List to TABL

Note that there have been changes to Safe Links policy for Microsoft Defender for Office 365 (MDO).

Previously you could add URLs to the Safe Links policy to control how MDO would process the URLs.  As part of this change the URL blocking is moving to the Tenant Allow Block List (TABL).

Below is a screenshot showing that a previously entered URL needs to be migrated to TABL.

 

Migration of MDO Global Block List to TABL

Learn more

 

&nb… Read the rest “Migrate Safe Links Block Settings to TABL”

5

Implementing Exchange DownloadDomain Security

Posted on by Rhoderick Milne [MSFT]
Implement Exchange DownloadDomain

In the field, I’m seeing multiple customers that are struggling to implement the DownloadDomain feature. It does require a little prep work and it is not as simple as just running a single command in Exchange to flip the setting on.

In order to mitigate and issue with OWA, it is necessary to create an additional CAS namespace that will be used for downloading attachments from OWA.  This will requir… Read the rest “Implementing Exchange DownloadDomain Security”

2

Exchange 2019 Point of No Return

Posted on by Rhoderick Milne [MSFT]
Exchange 2019 PrepareAD - The Point of No Return

When designing an upgrade strategy from an older version of Exchange to a newer one, a question that needs to be addressed is do we need to introduce a version of Exchange that may not currently be present?  This may be when upgrading from Exchange 2013 to Exchange 2019.  If that organisation currently does not have any Exchange 2016 servers, you need to evaluate if there may be a future requireme… Read the rest “Exchange 2019 Point of No Return”

0

Upgrade to Azure AD Connect 2.0

Posted on by Rhoderick Milne [MSFT]
Azure AD Connect Upgrade to 2.X

When delivering Office 365 Security Optimisation Assessments (SOA) to customers, one of the control items is the version of Azure AD Connect deployed along with some related configuration elements.  In many cases, Azure AD Connect is not updated to a build that resolves both security and feature issues.  Why is Azure AD Connect not current?  Good question.

There are two main scenarios that I see rig… Read the rest “Upgrade to Azure AD Connect 2.0”

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Joys of Server 2012 R2 TLS Defaults in June 2022

Posted on by Rhoderick Milne [MSFT]
Server 2012 R2 SSLLabs Report

Windows Server 2012 R2 was a great platform and was very widly adopted.  Unlike it’s less popular step-sister, Server 2012.  At least the R2 product had a start button, rather than the start pixel….

However, it really does show its age when viewed under a modern security lens.  Unsurprisingly, things have changed from a security perspective over the last decade. Not all of the Server 2012 R2 defaul… Read the rest “Joys of Server 2012 R2 TLS Defaults in June 2022”

1

Remediate SWEET32 — Disable TLS_RSA_WITH_3DES_EDE_CBC_SHA For Windows Server 2012 R2

Posted on by Rhoderick Milne [MSFT]
Remediate Sweet32

Admins have become very aware of the need to adjust the Schannel protocol settings for TLS to enable TLS 1.2 and to disable older versions.  However, the cipher suites do not always receive the same amount of attention and may be left at their default values.

If you are reading this post there is a good chance that your security auditors have flagged a weak cipher is enabled on your server, and the… Read the rest “Remediate SWEET32 — Disable TLS_RSA_WITH_3DES_EDE_CBC_SHA For Windows Server 2012 R2”