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V-278675

CAT II (Medium)

Microsoft Defender AV must report Dynamic Signature dropped events.

Rule ID

SV-278675r1190765_rule

STIG

Microsoft Defender Antivirus Security Technical Implementation Guide

Version

V2R8

CCIs

CCI-001170

Discussion

Microsoft Defender Antivirus logs "Dynamic Signature dropped" events when it blocks or removes a file based on a dynamically updated signature, but the signature itself is dropped, meaning it was not fully processed or applied. This can indicate a potential issue with signature updates or the system's ability to handle them.

Check Content

Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Reporting >> Configure whether to report Dynamic Signature dropped events 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\Reporting

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

If the value is 0, this is a finding.

Fix Text

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Reporting >> Configure whether to report Dynamic Signature dropped events to "Enabled".