Microsoft Defender AV must be configured to check for definition updates daily.

Documentable No

Rule ID SV-213454r961161_rule

CCI References

CCI-001308

Discussion

This policy setting allows specifying the day of the week on which to check for definition updates. The check can also be configured to run every day or to never run at all. This setting can be configured with the following ordinal number values: (0x0) Every Day (default) (0x1) Sunday (0x2) Monday (0x3) Tuesday (0x4) Wednesday (0x5) Thursday (0x6) Friday (0x7) Saturday (0x8) Never If this setting is enabled, the check for definition updates will occur at the frequency specified. If this setting is disabled or not configured, the check for definition updates will occur at a default frequency.

Check Procedure

Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Security Intelligence Updates >> "Specify the day of the week to check for security intelligence updates" is set to "Enabled" and "Every Day" is selected in the drop-down box.
  
Procedure: Use the Windows Registry Editor to navigate to the following key: 
HKLM\Software\Policies\Microsoft\Windows Defender\Signature Updates

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

Fix Action

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Signature Updates >> "Specify the day of the week to check for definition updates" to "Enabled" and select "Every Day" in the drop-down box.