Microsoft Defender AV must be configured to always enable real-time protection.

Documentable No

Rule ID SV-213445r961194_rule

CCI References

CCI-001242

Discussion

This policy setting turns off real-time protection prompts for known malware detection. Microsoft Defender Antivirus alerts when malware or potentially unwanted software attempts to install itself or to run on your computer. If this policy setting is enabled, Microsoft Defender Antivirus will not prompt users to take actions on malware detections. If this policy setting is disabled or not configured, Microsoft Defender Antivirus will prompt users to take actions on malware detections.

Check Procedure

Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Real-time Protection >> "Turn off real-time protection" is set to "Disabled" or "Not Configured".
 
Procedure: Use the Windows Registry Editor to navigate to the following key: 
HKLM\Software\Policies\Microsoft\Windows Defender\Real-Time Protection

Criteria: If the value "DisableRealtimeMonitoring" is REG_DWORD = 0, this is not a finding.

If the value does not exist, this is not a finding.

If the value is 1, this is a finding.

Fix Action

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Real-time Protection >> "Turn off real-time protection" to "Disabled" or "Not Configured".