Information
This setting configures if guests who use a verification code to access the site or links are required to reauthenticate after a set number of days.
The recommended state is 15 or less.
Rationale:
By increasing the frequency of times guests need to reauthenticate this ensures guest user access to data is not prolonged beyond an acceptable amount of time.
Impact:
Guests who use Microsoft 365 in their organization can sign in using their work or school account to access the site or document. After the one-time passcode for verification has been entered for the first time, guests will authenticate with their work or school account and have a guest account created in the host's organization.
Note: If OneDrive and SharePoint integration with Entra ID B2B is enabled as per the CIS Benchmark the one-time-passcode experience will be replaced. Please visit Secure external sharing in SharePoint - SharePoint in Microsoft 365 | Microsoft Learn for more information.
NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.
Solution
To remediate using the UI:
Navigate to SharePoint admin center https://admin.microsoft.com/sharepoint
Click to expand Policies > Sharing.
Scroll to and expand More external sharing settings.
Set People who use a verification code must reauthenticate after this many days to 15 or less.
To remediate using PowerShell:
Connect to SharePoint Online service using Connect-SPOService.
Run the following cmdlet:
Set-SPOTenant -EmailAttestationRequired $true -EmailAttestationReAuthDays 15
Default Value:
EmailAttestationRequired : False
EmailAttestationReAuthDays : 30