2.3 Ensure Safe Links for Office Applications is Enabled

Warning! Audit Deprecated

This audit has been deprecated and will be removed in a future update.

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Information

Enabling Safe Links policy for Office applications allows URL's that exist inside of Office documents and email applications opened by Office, Office Online and Office mobile to be processed against Defender for Office time-of-click verification and rewritten if required.

Note: E5 Licensing includes a number of Built-in Protection policies. When auditing policies note which policy you are viewing, and keep in mind CIS recommendations often extend the Default or Build-in Policies provided by MS. In order to Pass the highest priority policy must match all settings recommended.

Rationale:

Safe Links for Office applications extends phishing protection to documents and emails that contain hyperlinks, even after they have been delivered to a user.

Impact:

User impact associated with this change is minor - users may experience a very short delay when clicking on URLs in Office documents before being directed to the requested site. Users should be informed of the change as, in the event a link is unsafe and blocked, they will receive a message that it has been blocked.

NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.

Solution

To enable Defender for Office Safe Links policy for Office, use the Microsoft 365 Admin Center:

Under Admin centers click Security.

Under Email & collaboration select Policies & rules

Select Threat policies then Safe Links

Click on the policy, a new pane should open on the right hand side.

Under Protection settings click Edit protection settings

Ensure the follow boxes are checked:

On: Safe Links checks a list of known, malicious links when users click links in email. URLs are rewritten by default

Apply Safe Links to email messages sent within the organization

Apply real-time URL scanning for suspicious links and links that point to files

Wait for URL scanning to complete before delivering the message

On: Safe Links checks a list of known, malicious links when users click links in Microsoft Teams. URLs are not rewritten

On: Safe Links checks a list of known, malicious links when users click links in Microsoft Office apps. URLs are not rewritten

Under Click protection settings check Track user clicks and uncheck Let users click through to the original URL

Select Save

To enable the Safe Links policy for Office 365, use the Exchange Online PowerShell Module:

Connect using Connect-ExchangeOnline.

Run the following PowerShell command:

New-SafeLinksPolicy -Name 'My SafeLinks Policy' -EnableSafeLinksForEmail $true -EnableSafeLinksForTeams $true -EnableSafeLinksForOffice $true -ScanUrls $true -DeliverMessageAfterScan $true -EnableForInternalSenders $true -AllowClickThrough $false

See Also

https://workbench.cisecurity.org/files/4073