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Is ADFS now dead?

For those of you keeping an eager eye on cybersecurity, NCSE published some new guidance for securing Office 365 earlier this year. This new guidance includes one significant change from Microsoft, which some may find a little controversial.

Microsoft now recommends that hybrid environments – i.e. those that use Active Directory Domain Services and Azure AD – should prefer native authentication against Azure AD rather than ADFS.

In Microsoft-speak this is ‘Seamless SSO with Password Hash Sync’, configured to use either per-user or Conditional Access MFA.

Password synchronisation with the cloud can feel like a scary thing to do, but in actuality, organisations using Azure AD as their primary authentication source will lower their risk compared with ADFS.

This is because:

  • It’s the hashes of your password hashes that are sent to Azure AD, and not the reusable NTLM hashes commonly discussed in “pass the hash” attacks. This means that the credentials sent to Azure AD can’t be used to authenticate to any of your on-premise infrastructures that rely on Active Directory.
  • We are already relying on Azure AD to make access control decisions regulating who can see which data, hosted in Office 365. So we already need to trust that it’s built and operated securely. Storing password hashes doesn’t change that security requirement.
  • The availability of Office 365 will no longer be affected by any outages or downtime suffered by your on-premise ADFS or Active Directory infrastructure.

For those interested, the new Microsoft guidance can be found here:  It’s a brave new world out there!

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