A WDAC audit-mode policy that will log all non-Windows-signed driver loads and any driver that is not WHQL or EV signed.

Non_Microsoft_Driver_Load_Audit.xml

<?xml version="1.0" encoding="utf-8"?>
<SiPolicy xmlns="urn:schemas-microsoft-com:sipolicy">
  <VersionEx>10.0.0.0</VersionEx>
  <PolicyTypeID>{A244370E-44C9-4C06-B551-F6016E563076}</PolicyTypeID>
  <PlatformID>{2E07F7E4-194C-4D20-B7C9-6F44A6C5A234}</PlatformID>
  <Rules>
    <Rule>
      <Option>Enabled:Unsigned System Integrity Policy</Option>
    </Rule>
    <Rule>
      <Option>Enabled:Audit Mode</Option>
    </Rule>
    <Rule>
      <Option>Enabled:Advanced Boot Options Menu</Option>
    </Rule>
    <Rule>
      <Option>Required:WHQL</Option>
    </Rule>
    <Rule>
      <Option>Required:EV Signers</Option>
    </Rule>
    <Rule>
      <Option>Enabled:Update Policy No Reboot</Option>
    </Rule>
  </Rules>

  <!--EKUS-->
  <EKUs>
    <EKU ID="ID_EKU_WINDOWS" Value="010A2B0601040182370A0306" />
    <EKU ID="ID_EKU_ELAM"    Value="010A2B0601040182373D0401" />
    <EKU ID="ID_EKU_HAL_EXT" Value="010a2b0601040182373d0501" />
  </EKUs>
  
  <!--Signers-->
  <Signers>
    <Signer ID="ID_SIGNER_WINDOWS_PRODUCTION" Name="Microsoft Product Root 2010 Windows EKU">
      <CertRoot Type="Wellknown" Value="06" />
      <CertEKU ID="ID_EKU_WINDOWS" />
    </Signer>
    <Signer ID="ID_SIGNER_ELAM_PRODUCTION" Name="Microsoft Product Root 2010 ELAM EKU">
      <CertRoot Type="Wellknown" Value="06" />
      <CertEKU ID="ID_EKU_ELAM" />
    </Signer>
    <Signer ID="ID_SIGNER_HAL_PRODUCTION" Name="Microsoft Product Root 2010 HAL EKU">
      <CertRoot Type="Wellknown" Value="06" />
      <CertEKU ID="ID_EKU_HAL_EXT" />
    </Signer>
  </Signers>
  
  <SigningScenarios>
    <!--Kernel Mode Signing Scenario-->
    <SigningScenario Value="131" ID="ID_SIGNINGSCENARIO_KMCI" FriendlyName="Kernel Mode Signing Scenario">
      <ProductSigners>
        <AllowedSigners>
          <AllowedSigner SignerId="ID_SIGNER_WINDOWS_PRODUCTION" />
          <AllowedSigner SignerId="ID_SIGNER_ELAM_PRODUCTION" />
          <AllowedSigner SignerId="ID_SIGNER_HAL_PRODUCTION" />
        </AllowedSigners>
      </ProductSigners>
    </SigningScenario>
    
    <!--User Mode Signing Scenario-->
    <SigningScenario Value="12" ID="ID_SIGNINGSCENARIO_UMCI" FriendlyName="User Mode Signing Scenario">
      <ProductSigners />
    </SigningScenario>
  </SigningScenarios>
  <UpdatePolicySigners>
  </UpdatePolicySigners>

  <CiSigners />

  <HvciOptions>0</HvciOptions>
  <Settings>
    <Setting Provider="PolicyInfo" Key="Information" ValueName="Name">
      <Value>
        <String>DefaultWindowsAudit</String>
      </Value>
    </Setting>
    <Setting Provider="PolicyInfo" Key="Information" ValueName="Id">
      <Value>
        <String>031017</String>
      </Value>
    </Setting>
  </Settings>
</SiPolicy>