Detections
Analytics
2.1.1 Ensure Safe Links for Office Applications is Enabled
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 create a Safe Links policy:Navigate to Microsoft 365 Defender https://security.microsoft.com
Under Email & collaboration select Policies & rules
Select Threat policies then Safe Links
Click on +Create
Name the policy then click Next
In Domains select all valid domains for the organization and Next
Ensure the following URL & click protection settings are defined:
Checked On: Safe Links checks a list of known, malicious links when users click links in email. URLs are rewritten by default
Checked Apply Safe Links to email messages sent within the organization
Checked Apply real-time URL scanning for suspicious links and links that point to files
Checked Wait for URL scanning to complete before delivering the message
Unchecked Do not rewrite URLs, do checks via Safe Links API only.
Teams
Checked On: Safe Links checks a list of known, malicious links when users click links in Microsoft Teams. URLs are not rewritten
Office 365 Apps
Checked On: Safe Links checks a list of known, malicious links when users click links in Microsoft Office apps. URLs are not rewritten
Click protection settings
Checked Track user clicks
Unchecked Let users click through the original URL
There is no recommendation for organization branding.
Click Next twice and finally Submit
To create a Safe Links policy using the Exchange Online PowerShell Module:
Connect using Connect-ExchangeOnline.
Run the following PowerShell script to create a policy at highest priority that will apply to all valid domains on the tenant:
# Create the Policy
$params = @{
Name = 'CIS SafeLinks Policy'
EnableSafeLinksForEmail = $true
EnableSafeLinksForTeams = $true
EnableSafeLinksForOffice = $true
TrackClicks = $true
AllowClickThrough = $false
ScanUrls = $true
EnableForInternalSenders = $true
DeliverMessageAfterScan = $true
DisableUrlRewrite = $false
}
New-SafeLinksPolicy @params
# Create the rule for all users in all valid domains and associate with Policy
New-SafeLinksRule -Name 'CIS SafeLinks' -SafeLinksPolicy 'CIS SafeLinks Policy' -RecipientDomainIs (Get-AcceptedDomain).Name -Priority 0
See Also
Item Details
Audit Name: CIS Microsoft 365 Foundations E5 L2 v3.1.0
Category: SYSTEM AND INFORMATION INTEGRITY
References: 800-53|SI-3, CSCv7|7.4
Plugin: microsoft_azure
Control ID: 55e8c893b8666f23f21aa62c64aca2b6ebda39649fe8d2d5da14faee563a285f