Microsoft Defender AV must scan excluded files and directories during quick scans.

Documentable No

Rule ID SV-278676r1144075_rule

CCI References

CCI-001242

Discussion

In Microsoft Defender Antivirus, when an exclusion for a file or folder is created, it will generally be skipped during both real-time protection and on-demand scans (including quick scans and full scans). However, with newer releases, the option exists to configure quick scans to include files and directories that are otherwise excluded from real-time protection.

Check Procedure

Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Scan >> Scan excluded files and directories during quick scans is set to "Enabled"; otherwise, this is a finding.

Procedure: Use the Windows Registry Editor to navigate to the following key: 
HKLM\Software\Policies\Microsoft\Windows Defender\Scan

Criteria: If the value "QuickScanIncludeExclusions" is REG_DWORD = 1, this is not a finding.

If the value is 0, this is a finding.

Fix Action

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Scan >> Scan excluded files and directories during quick scans to "Enabled".

Click "OK".

Click "Apply".