Security

Security related items and thoughts

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Enable DMARC For OnMicrosoft.com Domains

Posted on by Rhoderick Milne [MSFT]
DMARC Record For onmicrosoft.com Domain

It is possible to add a Domain Based Message Authentication Reporting and Conformance (DMARC) record for your onmicrosoft.com domain in M365.  Is that a good thing?

Well, your viewpoint may depend on your experiences with this domain.  If you actually use the onmicrosoft.com domain to send email, then yes!  Adding the DMARC record enables the DMARC alignment check to pass and the mail to be success… Read the rest “Enable DMARC For OnMicrosoft.com Domains”

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How To Generate File Hash Using Certutil

Posted on by Rhoderick Milne [MSFT]
Create File Hash using Certutil

Windows has the ability to easily generate a hash for a given file using the Certutil.exe utility.  Administrators may have previously used to this tool when they need to generate TLS certificates or to perform other tasks against AD Certificate Services.  As an example of the former, this was a common task for AD FS certificates as described in this post.

To generate the file hash we will use the … Read the rest “How To Generate File Hash Using Certutil”

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Quick Tip – Easily Allow JIT to Azure VMs In A Resource Group

Posted on by Rhoderick Milne [MSFT]
Azure Portal Connect to VM

Controlling connections to Azure VMs using the just in time (JIT) policy of Microsoft Defender for Cloud (MDC) certainly improves the overall security of the Azure resource.  However, then having to enable JIT on a given VM runs into issues pretty quickly.

Azure Portal Too Permissive

Who thought it was a great idea to have “All configured IPs” as the default option? No thanks – I do not want to enab… Read the rest “Quick Tip – Easily Allow JIT to Azure VMs In A Resource Group”

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Check If AD FS WSTrust Endpoint Enabled

Posted on by Rhoderick Milne [MSFT]
Check WSTrust Endpoint Configuration

Active Directory Federation Services (AD FS) uses endpoints to provide access to features.  There are a series of different endpoints which each serve a different purpose from password reset, publishing federation metadata or multiple web services protocols.  It is important to ensure that only the required features are actually enabled, and also if those features are to be made available internal… Read the rest “Check If AD FS WSTrust Endpoint Enabled”

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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”

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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”

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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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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”

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SSL Labs Scan Outlook.Office365.com–June 2022

Posted on by Rhoderick Milne [MSFT]
SSLLabs Scan Outlook.Office365.com June 2022

This post is a scan of Outlook.office365.com taken with the SSLLabs.com scan tool which analyses the TLS configuration of the server.

 

 

Deprecating support for 3DES

Since October 31, 2018, Office 365 no longer supports the use of 3DES cipher suites for communication to Office 365. More specifically, Office 365 no longer supports the TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher suite. Since Februar… Read the rest “SSL Labs Scan Outlook.Office365.com–June 2022”