Detections
Analytics

2.1.7 (L2) Ensure that an anti-phishing policy has been created

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Information

By default, Office 365 includes built-in features that help protect users from phishing attacks. Set up anti-phishing polices to increase this protection, for example by refining settings to better detect and prevent impersonation and spoofing attacks. The default policy applies to all users within the organization and is a single view to fine-tune anti-phishing protection. Custom policies can be created and configured for specific users, groups or domains within the organization and will take precedence over the default policy for the scoped users.

Protects users from phishing attacks (like impersonation and spoofing) and uses safety tips to warn users about potentially harmful messages.

Solution

To remediate using the UI:

 - Navigate to Microsoft 365 Defender https://security.microsoft.com.
 - Click to expand Email & collaboration select Policies & rules
 - Select Threat policies.
 - Under Policies select Anti-phishing and click Create.
 - Name the policy, continuing and clicking Next as needed:
 - Add Groups and/or Domains that contain a majority of the organization.
 - Set Phishing email threshold to 3 - More Aggressive
 - Check Enable users to protect and add up to 350 users.
 - Check Enable domains to protect and check Include domains I own.
 - Check Enable mailbox intelligence (Recommended).
 - Check Enable Intelligence for impersonation protection (Recommended).
 - Check Enable spoof intelligence (Recommended).

 - Under Actions configure the following:
 - Set If a message is detected as user impersonation to Quarantine the message.
 - Set If a message is detected as domain impersonation to Quarantine the message.
 - Set If Mailbox Intelligence detects an impersonated user to Quarantine the message.
 - Leave Honor DMARC record policy when the message is detected as spoof checked.
 - Check Show first contact safety tip (Recommended).
 - Check Show user impersonation safety tip.
 - Check Show domain impersonation safety tip.
 - Check Show user impersonation unusual characters safety tip.

 - Finally click Next and Submit the policy.

Note: DefaultFullAccessWithNotificationPolicy is suggested but not required. Users will be notified that impersonation emails are in the Quarantine.

To remediate using PowerShell:

 - Connect to Exchange Online service using Connect-ExchangeOnline.
 - Run the following Exchange Online PowerShell script to create an AntiPhish policy:

# Create the Policy
$params = @{
 Name = "CIS AntiPhish Policy"
 PhishThresholdLevel = 3
 EnableTargetedUserProtection = $true
 EnableOrganizationDomainsProtection = $true
 EnableMailboxIntelligence = $true
 EnableMailboxIntelligenceProtection = $true
 EnableSpoofIntelligence = $true
 TargetedUserProtectionAction = 'Quarantine'
 TargetedDomainProtectionAction = 'Quarantine'
 MailboxIntelligenceProtectionAction = 'Quarantine'
 TargetedUserQuarantineTag = 'DefaultFullAccessWithNotificationPolicy'
 MailboxIntelligenceQuarantineTag = 'DefaultFullAccessWithNotificationPolicy'
 TargetedDomainQuarantineTag = 'DefaultFullAccessWithNotificationPolicy'
 EnableFirstContactSafetyTips = $true
 EnableSimilarUsersSafetyTips = $true
 EnableSimilarDomainsSafetyTips = $true
 EnableUnusualCharactersSafetyTips = $true
 HonorDmarcPolicy = $true
}

New-AntiPhishPolicy @params

# Create the rule for all users in all valid domains and associate with Policy
New-AntiPhishRule -Name $params.Name -AntiPhishPolicy $params.Name -RecipientDomainIs (Get-AcceptedDomain).Name -Priority 0
 - The new policy can be edited in the UI or via PowerShell.

Note: Remediation guidance is intended to help create a qualifying AntiPhish policy that meets the recommended criteria while protecting the majority of the organization. It's understood some individual user exceptions may exist or exceptions for the entire policy if another product acts as a similar control.

Impact:

Mailboxes that are used for support systems such as helpdesk and billing systems send mail to internal users and are often not suitable candidates for impersonation protection. Care should be taken to ensure that these systems are excluded from Impersonation Protection.

See Also

https://workbench.cisecurity.org/benchmarks/22162

Item Details

References: CSCv7|7

Plugin: microsoft_azure

Control ID: 39863d358246d690b2a44f12c2d428f73ffdbcc257a4bbc8c1ad06e31ec51e37