Windows Defender Denial of Service Vulnerability Audit

Find Vulnerable Windows Defender Installations

Microsoft released a new update for the Windows defender engine to fix a critical vulnerability (CVE-2019-1255). The latest engine version 1.1.16400.2 fixes the issue, however, it might not be so straight forward to view exactly which machines still need to be updated. You can learn more about it in our Windows Defender flaw blog post.

Fortunately, with the audit below, you can get an overview of your environment and whether the Windows defender engine has been updated or not. This way you can monitor the update progress and identify assets that might have issues receiving the automatic Windows defender updates.

To monitor the update process for the Windows Defender flaw, CVE-2019-1255, you will have to add the following registry keys and value names to custom registry scanning configuration.
Rootkey: HKEY_LOCAL_MACHINE
Regpath: SOFTWARE\Microsoft\Windows Defender\Signature Updates
Regvalue: EngineVersion

Rootkey: HKEY_LOCAL_MACHINE
Regpath: SOFTWARE\Microsoft\Microsoft Antimalware\Signature Updates
Regvalue: EngineVersion

Windows Defender Vulnerability audit

Windows Defender Engine Version Query

Select Top 1000000 tsysOS.Image As icon,
  tblAssets.AssetID,
  tblAssets.AssetName,
  tblAssets.Domain,
  tblAssets.Username,
  tblAssets.Userdomain,
  tblAssets.IPAddress,
  SubQuery1.Regkey,
  SubQuery1.Valuename,
  SubQuery1.Value As EngineVersion,
  Case
    When SubQuery1.EngineVersion >= 11164002 Then 'Safe'
    When SubQuery1.EngineVersion < 11164002 Then 'Vulnerable'
    When SubQuery2.EngineVersion >= 11164002 Then 'Safe'
    When SubQuery2.EngineVersion < 11164002 Then 'Vulnerable'
    Else 'RegKey not found'
  End As Status,
  tblAssets.Lastseen,
  tblAssets.Lasttried,
  TsysLastscan.Lasttime As LastRegistryScan,
  Case
    When TsysLastscan.Lasttime < GetDate() - 1 Then
      'Last registry scan more than 24 hours ago! Scanned registry information may not be up-to-date. Try rescanning this machine.'
  End As Comment,
  Case
    When SubQuery1.EngineVersion >= 11164002 Then '#d4f4be'
    When SubQuery1.EngineVersion < 11164002 Then '#ffadad'
    When SubQuery2.EngineVersion >= 11164002 Then '#d4f4be'
    When SubQuery2.EngineVersion < 11164002 Then '#ffadad'
    Else ''
  End As backgroundcolor
From tblAssets
  Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
  Inner Join tsysOS On tsysOS.OScode = tblAssets.OScode
  Inner Join TsysLastscan On tblAssets.AssetID = TsysLastscan.AssetID
  Inner Join TsysWaittime On TsysWaittime.CFGCode = TsysLastscan.CFGcode
  Left Join (Select Top 1000000 tblRegistry.AssetID,
        tblRegistry.Regkey,
        tblRegistry.Valuename,
        tblRegistry.Value,
        Convert(bigint,Replace(tblRegistry.Value, '.', '')) As EngineVersion,
        tblRegistry.Lastchanged
      From tblRegistry
      Where
        tblRegistry.Regkey Like
        '%SOFTWARE\Microsoft\Windows Defender\Signature Updates' And
        tblRegistry.Valuename = 'EngineVersion') SubQuery1 On
    SubQuery1.AssetID = tblAssets.AssetID
  Left Join (Select Top 1000000 tblRegistry.AssetID,
        tblRegistry.Regkey,
        tblRegistry.Valuename,
        tblRegistry.Value,
        Convert(bigint,Replace(tblRegistry.Value, '.', '')) As EngineVersion,
        tblRegistry.Lastchanged
      From tblRegistry
      Where
        tblRegistry.Regkey Like
        '%SOFTWARE\Microsoft\Microsoft Antimalware\Signature Updates' And
        tblRegistry.Valuename = 'EngineVersion') SubQuery2 On
    SubQuery2.AssetID = tblAssets.AssetID
Where tblAssetCustom.State = 1 And TsysWaittime.CFGname = 'registry' And
  tsysOS.OSname <> 'Win 2000 S' And tsysOS.OSname Not Like '%XP%' And
  tsysOS.OSname Not Like '%2003%' And (Not tsysOS.OSname Like 'Win 7%'
    Or Not tblAssets.SP = 0)
Order By tblAssets.Domain,
  tblAssets.AssetName

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