Windows Defender AV spyware definition age must not exceed 7 days.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-75241	WNDF-AV-000028	SV-89921r2_rule		High

Description
This policy setting allows you to define the number of days that must pass before spyware definitions are considered out of date. If definitions are determined to be out of date this state may trigger several additional actions including falling back to an alternative update source or displaying a warning icon in the user interface. By default this value is set to 14 days. If you enable this setting spyware definitions will be considered out of date after the number of days specified have passed without an update. If you disable or do not configure this setting spyware definitions will be considered out of date after the default number of days have passed without an update.

Description

This policy setting allows you to define the number of days that must pass before spyware definitions are considered out of date. If definitions are determined to be out of date this state may trigger several additional actions including falling back to an alternative update source or displaying a warning icon in the user interface. By default this value is set to 14 days. If you enable this setting spyware definitions will be considered out of date after the number of days specified have passed without an update. If you disable or do not configure this setting spyware definitions will be considered out of date after the default number of days have passed without an update.

STIG	Date
MS Windows Defender Antivirus Security Technical Implementation Guide	2019-12-12

Details

Check Text ( C-75033r3_chk )
Verify the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Signature Updates -> "Define the number of days before spyware definitions are considered out of date" is set to "Enabled" and "7"or less selected in the drop down box (excluding "0", which is unacceptable). Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows Defender\Signature Updates Criteria: If the value "ASSignatureDue" is REG_DWORD = 7, this is not a finding. A value of 1 - 6 is also acceptable and not a finding. A value of 0 is a finding. A value higher than 7 is a finding.

Check Text ( C-75033r3_chk )

Verify the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Signature Updates -> "Define the number of days before spyware definitions are considered out of date" is set to "Enabled" and "7"or less selected in the drop down box (excluding "0", which is unacceptable).

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

Criteria: If the value "ASSignatureDue" is REG_DWORD = 7, this is not a finding.

A value of 1 - 6 is also acceptable and not a finding.

A value of 0 is a finding.

A value higher than 7 is a finding.

Fix Text (F-81851r2_fix)
Set the policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Antivirus -> Signature Updates -> "Define the number of days before spyware definitions are considered out of date" to "Enabled" and select "7" or less in the drop down box. Do not select a value of 0. This disables the option.