A Device Guard policy in enforcement mode that just works. It permits execution of only enough to boot the OS, run Windows code, and run Store apps.

BaseEnforcementPolicy.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:Advanced Boot Options Menu</Option>
    </Rule>
    <Rule>
      <Option>Required:Enforce Store Applications</Option>
    </Rule>
    <Rule>
      <Option>Enabled:UMCI</Option>
    </Rule>
    <Rule>
      <Option>Enabled:Inherit Default Policy</Option>
    </Rule>
    <Rule>
      <Option>Disabled:Flight Signing</Option>
    </Rule>
  </Rules>
  <!--EKUS-->
  <EKUs>
    <EKU ID="ID_EKU_WINDOWS" Value="010A2B0601040182370A0306" FriendlyName="Windows System Component Verification - 1.3.6.1.4.1.311.10.3.6" />
    <EKU ID="ID_EKU_WHQL" Value="010A2B0601040182370A0305" FriendlyName="Windows Hardware Driver Verification - 1.3.6.1.4.1.311.10.3.5" />
    <EKU ID="ID_EKU_ELAM" Value="010A2B0601040182373D0401" FriendlyName="Early Launch Antimalware Driver - 1.3.6.1.4.1.311.61.4.1" />
    <EKU ID="ID_EKU_HAL_EXT" Value="010A2B0601040182373D0501" FriendlyName="HAL Extension - 1.3.6.1.4.1.311.61.5.1" />
    <EKU ID="ID_EKU_STORE" Value="010A2B0601040182374C0301" FriendlyName="Windows Store EKU - 1.3.6.1.4.1.311.76.3.1" />
    <EKU ID="ID_EKU_DCODEGEN" Value="010A2B0601040182374C0501" FriendlyName="Dynamic Code Generation EKU - 1.3.6.1.4.1.311.76.5.1" />
    <EKU ID="ID_EKU_AM" Value="010A2B0601040182374C0B01" FriendlyName="AntiMalware EKU - 1.3.6.1.4.1.311.76.11.1" />
  </EKUs>
  <!--Signers-->
  <Signers>
    <Signer ID="ID_SIGNER_WHQL_MD5" Name="Microsoft Product Root WHQL EKU MD5">
      <CertRoot Type="Wellknown" Value="04" />
      <CertEKU ID="ID_EKU_WHQL" />
    </Signer>
    <Signer ID="ID_SIGNER_WHQL_MD5_USER" Name="Microsoft Product Root WHQL EKU MD5">
      <CertRoot Type="Wellknown" Value="04" />
      <CertEKU ID="ID_EKU_WHQL" />
    </Signer>
    <Signer ID="ID_SIGNER_WHQL_SHA1_USER" Name="Microsoft Product Root WHQL EKU SHA1">
      <CertRoot Type="Wellknown" Value="05" />
      <CertEKU ID="ID_EKU_WHQL" />
    </Signer>
    <Signer ID="ID_SIGNER_WHQL_SHA1" Name="Microsoft Product Root WHQL EKU SHA1">
      <CertRoot Type="Wellknown" Value="05" />
      <CertEKU ID="ID_EKU_WHQL" />
    </Signer>
    <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>
    <Signer ID="ID_SIGNER_WINDOWS_PRODUCTION_USER" Name="Microsoft Product Root 2010 Windows EKU">
      <CertRoot Type="Wellknown" Value="06" />
      <CertEKU ID="ID_EKU_WINDOWS" />
    </Signer>
    <Signer ID="ID_SIGNER_ELAM_PRODUCTION_USER" Name="Microsoft Product Root 2010 ELAM EKU">
      <CertRoot Type="Wellknown" Value="06" />
      <CertEKU ID="ID_EKU_ELAM" />
    </Signer>
    <Signer ID="ID_SIGNER_HAL_PRODUCTION_USER" Name="Microsoft Product Root 2010 HAL EKU">
      <CertRoot Type="Wellknown" Value="06" />
      <CertEKU ID="ID_EKU_HAL_EXT" />
    </Signer>
    <Signer ID="ID_SIGNER_WHQL_SHA2_USER" Name="Microsoft Product Root 2010 WHQL EKU">
      <CertRoot Type="Wellknown" Value="06" />
      <CertEKU ID="ID_EKU_WHQL" />
    </Signer>
    <Signer ID="ID_SIGNER_WHQL_SHA2" Name="Microsoft Product Root 2010 WHQL EKU">
      <CertRoot Type="Wellknown" Value="06" />
      <CertEKU ID="ID_EKU_WHQL" />
    </Signer>
    <Signer ID="ID_SIGNER_DCODEGEN" Name="MincryptKnownRootMicrosoftProductRoot2010">
      <CertRoot Type="Wellknown" Value="06" />
      <CertEKU ID="ID_EKU_DCODEGEN" />
    </Signer>
    <Signer ID="ID_SIGNER_AM" Name="MincryptKnownRootMicrosoftStandardRoot2011">
      <CertRoot Type="Wellknown" Value="07" />
      <CertEKU ID="ID_EKU_AM" />
    </Signer>
    <Signer ID="ID_SIGNER_DRM" Name="MincryptKnownRootMicrosoftDMDRoot2005">
      <CertRoot Type="Wellknown" Value="0C" />
    </Signer>
    <!-- Start: Flighting related signers -->
    <Signer ID="ID_SIGNER_WINDOWS_FLIGHT_ROOT" Name="Microsoft Flighting Root 2014 Windows EKU">
      <CertRoot Type="Wellknown" Value="0E" />
      <CertEKU ID="ID_EKU_WINDOWS" />
    </Signer>
    <Signer ID="ID_SIGNER_ELAM_FLIGHT" Name="Microsoft Flighting Root 2014 ELAM EKU">
      <CertRoot Type="Wellknown" Value="0E" />
      <CertEKU ID="ID_EKU_ELAM" />
    </Signer>
    <Signer ID="ID_SIGNER_HAL_FLIGHT" Name="Microsoft Flighting Root 2014 HAL EKU">
      <CertRoot Type="Wellknown" Value="0E" />
      <CertEKU ID="ID_EKU_HAL_EXT" />
    </Signer>
    <Signer ID="ID_SIGNER_WHQL_FLIGHT_SHA2" Name="Microsoft Flighting Root 2014 WHQL EKU">
      <CertRoot Type="Wellknown" Value="0E" />
      <CertEKU ID="ID_EKU_WHQL" />
    </Signer>
    <Signer ID="ID_SIGNER_WINDOWS_FLIGHT_ROOT_USER" Name="Microsoft Flighting Root 2014 Windows EKU">
      <CertRoot Type="Wellknown" Value="0E" />
      <CertEKU ID="ID_EKU_WINDOWS" />
    </Signer>
    <Signer ID="ID_SIGNER_ELAM_FLIGHT_USER" Name="Microsoft Flighting Root 2014 ELAM EKU">
      <CertRoot Type="Wellknown" Value="0E" />
      <CertEKU ID="ID_EKU_ELAM" />
    </Signer>
    <Signer ID="ID_SIGNER_HAL_FLIGHT_USER" Name="Microsoft Flighting Root 2014 HAL EKU">
      <CertRoot Type="Wellknown" Value="0E" />
      <CertEKU ID="ID_EKU_HAL_EXT" />
    </Signer>
    <Signer ID="ID_SIGNER_WHQL_FLIGHT_SHA2_USER" Name="Microsoft Flighting Root 2014 WHQL EKU">
      <CertRoot Type="Wellknown" Value="0E" />
      <CertEKU ID="ID_EKU_WHQL" />
    </Signer>
    <!-- End: Flighting related signers -->
    <Signer ID="ID_SIGNER_STORE" Name="Microsoft MarketPlace PCA 2011">
      <CertRoot Type="TBS" Value="FC9EDE3DCCA09186B2D3BF9B738A2050CB1A554DA2DCADB55F3F72EE17721378" />
      <CertEKU ID="ID_EKU_STORE" />
    </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" />
          <AllowedSigner SignerId="ID_SIGNER_WHQL_SHA2" />
          <AllowedSigner SignerId="ID_SIGNER_WHQL_SHA1" />
          <AllowedSigner SignerId="ID_SIGNER_WHQL_MD5" />
          <AllowedSigner SignerId="ID_SIGNER_WINDOWS_FLIGHT_ROOT" />
          <AllowedSigner SignerId="ID_SIGNER_ELAM_FLIGHT" />
          <AllowedSigner SignerId="ID_SIGNER_HAL_FLIGHT" />
          <AllowedSigner SignerId="ID_SIGNER_WHQL_FLIGHT_SHA2" />
        </AllowedSigners>
      </ProductSigners>
    </SigningScenario>
    <!--User Mode Signing Scenario-->
    <SigningScenario Value="12" ID="ID_SIGNINGSCENARIO_UMCI" FriendlyName="User Mode Signing Scenario">
      <ProductSigners>
        <AllowedSigners>
          <AllowedSigner SignerId="ID_SIGNER_WINDOWS_PRODUCTION_USER" />
          <AllowedSigner SignerId="ID_SIGNER_ELAM_PRODUCTION_USER" />
          <AllowedSigner SignerId="ID_SIGNER_HAL_PRODUCTION_USER" />
          <AllowedSigner SignerId="ID_SIGNER_WHQL_SHA2_USER" />
          <AllowedSigner SignerId="ID_SIGNER_WHQL_SHA1_USER" />
          <AllowedSigner SignerId="ID_SIGNER_WHQL_MD5_USER" />
          <AllowedSigner SignerId="ID_SIGNER_WINDOWS_FLIGHT_ROOT_USER" />
          <AllowedSigner SignerId="ID_SIGNER_ELAM_FLIGHT_USER" />
          <AllowedSigner SignerId="ID_SIGNER_HAL_FLIGHT_USER" />
          <AllowedSigner SignerId="ID_SIGNER_WHQL_FLIGHT_SHA2_USER" />
          <AllowedSigner SignerId="ID_SIGNER_STORE" />
          <AllowedSigner SignerId="ID_SIGNER_DRM" />
          <AllowedSigner SignerId="ID_SIGNER_DCODEGEN" />
          <AllowedSigner SignerId="ID_SIGNER_AM" />
        </AllowedSigners>
      </ProductSigners>
    </SigningScenario>
  </SigningScenarios>
  <UpdatePolicySigners>
  </UpdatePolicySigners>
  <!-- 

    CiSigners are signers that ConfigCI asks CI to trust for all builds, include 
    retail builds.
    
    Normally CiSigners is empty or only includes production signers. For enterprise
    ConfigCI policy, you may need to include enterprise signers. Just make sure it
    is understood that CiSigners will be trusted by CI for all builds.

-->
  <CiSigners>
    <!--
      Currently Centennial Apps are launched as Win32 Apps and signed by store certificate.
      We need to allow enterprise signing scenario to trust store certificate.
    -->
    <CiSigner SignerId="ID_SIGNER_STORE" />
  </CiSigners>
  <HvciOptions>0</HvciOptions>
  <Settings>
    <Setting Provider="PolicyInfo" Key="Information" ValueName="Name">
      <Value>
        <String>BaseWindowsDeviceGuardCIPolicy</String>
      </Value>
    </Setting>
  </Settings>
</SiPolicy>

Mr. Graeber,

Where did you get this list of wellknown certs from?

Best,
Kim

I think I found the answer. There copied from the examplepolicies I guess in C:\windows\Schemas\Codeintegrity\examplepolicies