TPM is a specialized hardware-protected logic that performs a series of hardware protected security operations including providing protected storage, random number generation, encryption, and signing.
**DHA (Device HealthAttestation) feature**The Device HealthAttestation (DHA) feature enables enterprise IT administrators to monitor the security posture of managed devices remotely by using hardware (TPM) protected and attested data via a tamper-resistant and tamper-evident communication channel.
**MAA-Session (Microsoft Azure Attestation service based device HealthAttestation session)**The Microsoft Azure Attestation service-based device HealthAttestation session (MAA-Session) describes the end-to-end communication flow that is performed in one device health attestation session.
**MAA-CSP Nodes (Microsoft Azure Attestation based Configuration Service Provider)**The Configuration Service Provider nodes added to Windows 11 to integrate with Microsoft Azure Attestation Service.
The following list of operations is performed by MAA-CSP:
Attestation flow can be broadly in three main steps:
The root node for the device HealthAttestation configuration service provider.
**TriggerAttestation** (Required)Node type: EXECUTE This node will trigger attestation flow by launching an attestation process. If the attestation process is launched successfully, this node will return code 202 indicating the request is received and being processed. Otherwise, an error will be returned.
Templated SyncML Call:
```xmlData fields:
Sample Data:
```json { "rpid" : "https://www.contoso.com/attestation", "endpoint" : "https://contoso.eus.attest.azure.net/attest/tpm?api-version=2020-10-01", "nonce" : "5468697320697320612054657374204e6f6e6365", "aadToken" : "dummytokenstring", "cv" : "testonboarded" } ``` **AttestStatus**Node type: GET This node will retrieve the status(HRESULT value) stored in registry updated by the attestation process triggered in the previous step. The status is always cleared prior to making the attest service call.
Templated SyncML Call:
```xmlSample Data:
``` If Successful: 0 If Failed: A corresponding HRESULT error code Example: 0x80072efd, WININET_E_CANNOT_CONNECT ``` **GetAttestReport**Node type: GET This node will retrieve the attestation report per the call made by the TriggerAttestation, if there is any, for the given MDM provider. The report is stored in a registry key in the respective MDM enrollment store.
Templated SyncML Call:
```xmlSample data:
``` If Success: JWT token: aaaaaaaaaaaaa.bbbbbbbbbbbbb.cccccccccc If failed: Previously cached report if available (the token may have already expired per the attestation policy). OR Sync ML 404 error if not cached report available. ``` **GetServiceCorrelationIDs**Node type: GET This node will retrieve the service-generated correlation IDs for the given MDM provider. If there are more than one correlation IDs, they are separated by “;” in the string.
Templated SyncML Call:
```xmlSample data:
> If success: > GUID returned by the attestation service: 1k9+vQOn00S8ZK33;CMc969r1JEuHwDpM > If Trigger Attestation call failed and no previous data is present. The field remains empty. > Otherwise, the last service correlation id will be returned. In a successful attestation there are two > calls between client and MAA and for each call the GUID is separated by semicolon. > **_Note:_** MAA CSP nodes are available on arm64 but is not currently supported. ### MAA CSP Integration StepsTPM is a specialized hardware-protected logic that performs a series of hardware protected security operations including providing protected storage, random number generation, encryption, and signing.
**DHA (Device HealthAttestation) feature**The Device HealthAttestation (DHA) feature enables enterprise IT administrators to monitor the security posture of managed devices remotely by using hardware (TPM) protected and attested data via a tamper-resistant and tamper-evident communication channel.
**DHA-Enabled device (Device HealthAttestation enabled device)**A Device HealthAttestation enabled (DHA-Enabled) device is a computing device (phone, desktop, laptop, tablet, server) that runs Windows 10 and supports TPM version 1.2 or 2.0.
**DHA-Session (Device HealthAttestation session)**The Device HealthAttestation session (DHA-Session) describes the end-to-end communication flow that is performed in one device health attestation session.
The following list of transactions is performed in one DHA-Session:
The following list of data is produced or consumed in one DHA-Transaction:
Device HealthAttestation enabled (DHA-Enabled) device management solution is a device management tool that is integrated with the DHA feature.
DHA-Enabled device management solutions enable enterprise IT managers to raise the security protection bar for their managed devices based on hardware (TPM) protected data that can be trusted even if a device is compromised by advanced security threats or running a malicious (jailbroken) operating system.
The following list of operations is performed by DHA-Enabled-MDM
The Device HealthAttestation Configuration Service Provider (DHA-CSP) uses a device’s TPM and firmware to measure critical security properties of the device’s BIOS and Windows boot, such that even on a system infected with kernel level malware or a rootkit, these properties cannot be spoofed.
The following list of operations is performed by DHA-CSP:
Device HealthAttestation Service (DHA-Service) validates the data it receives from DHA-CSP and issues a highly trusted hardware (TPM) protected report (DHA-Report) to DHA-Enabled device management solutions through a tamper resistant and tamper evident communication channel.
DHA-Service is available in two flavors: “DHA-Cloud” and “DHA-Server2016”. DHA-Service supports various implementation scenarios including cloud, on premises, air-gapped, and hybrid scenarios.
The following list of operations is performed by DHA-Service:
- Receives device boot data (DHA-BootData) from a DHA-Enabled device - Forwards DHA-BootData to Device Health Attestation Service (DHA-Service) - Receives an encrypted blob (DHA-EncBlob) from DHA-Service, and stores it in a local cache on the device - Receives attestation requests (DHA-Requests) from a DHA-Enabled-MDM, and replies with a device health report (DHA-Report) | DHA-Service type | Description | Operation cost |
|---|---|---|
| Device Health Attestation – Cloud (DHA-Cloud) |
DHA-Cloud is a Microsoft owned and operated DHA-Service that is:
| No cost |
| Device Health Attestation – On Premise (DHA-OnPrem) |
DHA-OnPrem refers to DHA-Service that is running on premises:
|
The operation cost of running one or more instances of Server 2016 on-premises. |
| Device Health Attestation - Enterprise-Managed Cloud (DHA-EMC) |
DHA-EMC refers to an enterprise-managed DHA-Service that is running as a virtual host/service on a Windows Server 2016 compatible - enterprise-managed cloud service, such as Microsoft Azure.
|
The operation cost of running Server 2016 on a compatible cloud service, such as Microsoft Azure. |
The root node for the device HealthAttestation configuration service provider.
**VerifyHealth** (Required)Notifies the device to prepare a device health verification request.
The supported operation is Execute.
**Status** (Required)Provides the current status of the device health request.
The supported operation is Get.
The following list shows some examples of supported values. For the complete list of status, see Device HealthAttestation CSP status and error codes.
- 0 - (HEALTHATTESTATION\_CERT\_RETRIEVAL_UNINITIALIZED): DHA-CSP is preparing a request to get a new DHA-EncBlob from DHA-Service - 1 - (HEALTHATTESTATION\_CERT\_RETRIEVAL_REQUESTED): DHA-CSP is waiting for the DHA-Service to respond back, and issue a DHA-EncBlob to the device - 2 - (HEALTHATTESTATION\_CERT\_RETRIEVAL_FAILED): A valid DHA-EncBlob could not be retrieved from the DHA-Service for reasons other than discussed in the DHA error/status codes - 3 - (HEALTHATTESTATION\_CERT\_RETRIEVAL_COMPLETE): DHA-Data is ready for pickup **ForceRetrieve** (Optional)Instructs the client to initiate a new request to DHA-Service, and get a new DHA-EncBlob (a summary of the boot state that is issued by DHA-Service). This option should only be used if the MDM server enforces a certificate freshness policy, which needs to force a device to get a fresh encrypted blob from DHA-Service.
Boolean value. The supported operation is Replace.
**Certificate** (Required)Instructs the DHA-CSP to forward DHA-Data to the MDM server.
Value type is b64. The supported operation is Get.
**Nonce** (Required)Enables MDMs to protect the device health attestation communications from man-in-the-middle type (MITM) attacks with a crypt-protected random value that is generated by the MDM Server.
The nonce is in hex format, with a minimum size of 8 bytes, and a maximum size of 32 bytes.
The supported operations are Get and Replace.
**CorrelationId** (Required)Identifies a unique device health attestation session. CorrelationId is used to correlate DHA-Service logs with the MDM server events and Client event logs for debug and troubleshooting.
Value type is integer, the minimum value is - 2,147,483,648 and the maximum value is 2,147,483,647. The supported operation is Get.
**HASEndpoint** (Optional)Identifies the fully qualified domain name (FQDN) of the DHA-Service that is assigned to perform attestation. If an FQDN is not assigned, DHA-Cloud (Microsoft owned and operated cloud service) will be used as the default attestation service.
Value type is string. The supported operations are Get and Replace. The default value is has.spserv.microsoft.com.
**TpmReadyStatus** (Required)Added in Windows 10, version 1607 March service release. Returns a bitmask of information describing the state of TPM. It indicates whether the TPM of the device is in a ready and trusted state.
Value type is integer. The supported operation is Get.
### **DHA-CSP integration steps** The following list of validation and development tasks are required for integrating the Microsoft Device Health Attestation feature with a Windows Mobile device management solution (MDM): 1. [Verify HTTPS access](#verify-access) 2. [Assign an enterprise trusted DHA-Service](#assign-trusted-dha-service) 3. [Instruct client to prepare DHA-data for verification](#prepare-health-data) 4. [Take action based on the clients response](#take-action-client-response) 5. [Instruct the client to forward DHA-data for verification](#forward-health-attestation) 6. [Post DHA-data to DHA-service](#forward-data-to-has) 7. [Receive response from DHA-service](#receive-has-response) 8. [Parse DHA-Report data. Take appropriate policy action based on evaluation results](#take-policy-action) Each step is described in detail in the following sections of this topic. ### **Step 1: Verify HTTPS access** Validate that both the MDM server and the device (MDM client) can access has.spserv.microsoft.com using the TCP protocol over port 443 (HTTPS). You can use OpenSSL to validate access to DHA-Service. Here is a sample OpenSSL command and the response that was generated by DHA-Service: ``` syntax PS C:\openssl> ./openssl.exe s_client -connect has.spserv.microsoft.com:443 CONNECTED(000001A8) --- Certificate chain 0 s:/CN=*.spserv.microsoft.com i:/C=US/ST=Washington/L=Redmond/O=Microsoft Corporation/OU=Microsoft IT/CN=Microsoft IT SSL SHA2 1 s:/C=US/ST=Washington/L=Redmond/O=Microsoft Corporation/OU=Microsoft IT/CN=Microsoft IT SSL SHA2 i:/C=IE/O=Baltimore/OU=CyberTrust/CN=Baltimore CyberTrust Root --- Server certificate -----BEGIN CERTIFICATE----- MIIGOTCCBCGgAwIBAgITWgAA1KJb40tpukQoewABAADUojANBgkqhkiG9w0BAQsFA4ICAQCJaKewFQuqQwR5fkAr9kZOmtq5fk03p82eHWLaftXlc4RDvVFp4a2ciSjZL8f3f+XWPVdUj9DAi3bCSddlrcNOPRXNepFC1OEmKtE9jM0r7M8qnqFkIfbNrVNUtPxHoraQeMIgbk0SHEOlShY2GXETVBqZdDZ5Rmk4rA+3ggoeV8hNzm2dfNp0iGSrZzawbLzWU1D2Tped1k5IV63yb+cU/TmM …………………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………………………………………………………………………… ……………2RXXwogn1UM8TZduCEjz+b05mAkvytugzzaI4wXkCP4OgNyy8gul2z5Gj/51pCTN -----END CERTIFICATE----- subject=/CN=*.spserv.microsoft.com issuer=/C=US/ST=Washington/L=Redmond/O=Microsoft Corporation/OU=Microsoft IT/CN=Microsoft IT SSL SHA2 --- No client certificate CA names sent Peer signing digest: SHA1 Server Temp Key: ECDH, P-384, 384 bits --- SSL handshake has read 3681 bytes and written 561 bytes New, TLSv1/SSLv3, Cipher is ECDHE-RSA-AES256-SHA384 Server public key is 2048 bit Secure Renegotiation IS supported Compression: NONE Expansion: NONE No ALPN negotiated SSL-Session: Protocol: TLSv1.2 Cipher: ECDHE-RSA-AES256-SHA384 Session-ID: B22300009621370F84A4A3A7D9FC40D584E047C090604E5226083A02ED239C93 Session-ID-ctx: Master-Key: 9E3F6BE5B3D3B55C070470CA2B62EF59CC1D5ED9187EF5B3D1BBF4C101EE90BEB04F34FFD748A13C92A387104B8D1DE7 Key-Arg: None PSK identity: None PSK identity hint: None SRP username: None Start Time: 1432078420 Timeout: 300 (sec) Verify return code: 20 (unable to get local issuer certificate) ``` ### **Step 2: Assign an enterprise trusted DHA-Service** There are three types of DHA-Service: - Device Health Attestation – Cloud (owned and operated by Microsoft) - Device Health Attestation – On Premise (owned and operated by an enterprise, runs on Windows Server 2016 on premises) - Device Health Attestation - Enterprise-Managed Cloud (owned and operated by an enterprise, runs on Windows Server 2016 compatible enterprise-managed cloud) DHA-Cloud is the default setting. No further action is required if an enterprise is planning to use Microsoft DHA-Cloud as the trusted DHA-Service provider. For DHA-OnPrem & DHA-EMC scenarios, send a SyncML command to the HASEndpoint node to instruct a managed device to communicate with the enterprise trusted DHA-Service. The following example shows a sample call that instructs a managed device to communicate with an enterprise-managed DHA-Service. ```xmlThe date and time DHA-report was evaluated or issued to MDM.
**AIKPresent**When an Attestation Identity Key (AIK) is present on a device, it indicates that the device has an endorsement key (EK) certificate. It can be trusted more than a device that doesn’t have an EK certificate.
If AIKPresent = True (1), then allow access.
If AIKPresent = False (0), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Allow conditional access based on other data points that are present at evaluation time. For example, other attributes on the health certificate, or a device's past activities and trust history. - Take one of the previous actions and additionally place the device in a watch list to monitor the device more closely for potential risks. **ResetCount** (Reported only for devices that support TPM 2.0)This attribute reports the number of times a PC device has hibernated or resumed.
**RestartCount** (Reported only for devices that support TPM 2.0)This attribute reports the number of times a PC device has rebooted
**DEPPolicy**A device can be trusted more if the DEP Policy is enabled on the device.
Data Execution Prevention (DEP) Policy defines is a set of hardware and software technologies that perform additional checks on memory to help prevent malicious code from running on a system. Secure boot allows a limited list on x86/amd64 and on ARM NTOS locks it to on.
DEPPolicy can be disabled or enabled by using the following commands in WMI or a PowerShell script:
- To disable DEP, type **bcdedit.exe /set {current} nx AlwaysOff** - To enable DEP, type **bcdedit.exe /set {current} nx AlwaysOn**If DEPPolicy = 1 (On), then allow access.
If DEPPolicy = 0 (Off), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Allow conditional access based on other data points that are present at evaluation time. For example, other attributes on the health certificate, or a device's past activities and trust history. - Take one of the previous actions and additionally place the device in a watch list to monitor the device more closely for potential risks. **BitLockerStatus** (at boot time)When BitLocker is reported "on" at boot time, the device is able to protect data that is stored on the drive from unauthorized access, when the system is turned off or goes to hibernation.
Windows BitLocker Drive Encryption, encrypts all data stored on the Windows operating system volume. BitLocker uses the TPM to help protect the Windows operating system and user data and helps to ensure that a computer is not tampered with, even if it is left unattended, lost, or stolen.
If the computer is equipped with a compatible TPM, BitLocker uses the TPM to lock the encryption keys that protect the data. As a result, the keys cannot be accessed until the TPM has verified the state of the computer.
If BitLockerStatus = 1 (On), then allow access.
If BitLockerStatus = 0 (Off), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Allow conditional access based on other data points that are present at evaluation time. For example, other attributes on the health certificate, or a device's past activities and trust history. - Take one of the previous actions and additionally place the device in a watch list to monitor the device more closely for potential risks. **BootManagerRevListVersion**This attribute indicates the version of the Boot Manager that is running on the device, to allow you to track and manage the security of the boot sequence/environment.
If BootManagerRevListVersion = [CurrentVersion], then allow access.
If BootManagerRevListVersion != [CurrentVersion], then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI and MBI assets - Place the device in a watch list to monitor the device more closely for potential risks. - Trigger a corrective action, such as informing the technical support team to contact the owner investigate the issue. **CodeIntegrityRevListVersion**This attribute indicates the version of the code that is performing integrity checks during the boot sequence. Using this attribute can help you detect if the device is running the latest version of the code that performs integrity checks, or if it is exposed to security risks (revoked) and enforce an appropriate policy action.
If CodeIntegrityRevListVersion = [CurrentVersion], then allow access.
If CodeIntegrityRevListVersion != [CurrentVersion], then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI and MBI assets - Place the device in a watch list to monitor the device more closely for potential risks. - Trigger a corrective action, such as informing the technical support team to contact the owner investigate the issue. **SecureBootEnabled**When Secure Boot is enabled the core components used to boot the machine must have correct cryptographic signatures that are trusted by the organization that manufactured the device. The UEFI firmware verifies this before it lets the machine start. If any files have been tampered with, breaking their signature, the system will not boot.
If SecureBootEnabled = 1 (True), then allow access.
If SecurebootEnabled = 0 (False), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Allow conditional access based on other data points that are present at evaluation time. For example, other attributes on the health certificate, or a device's past activities and trust history. - Take one of the previous actions and additionally place the device in a watch list to monitor the device more closely for potential risks. **BootDebuggingEnabled**Boot debug-enabled points to a device that is used in development and testing. Devices that are used for test and development typically are less secure: the device may run unstable code, or be configured with fewer security restrictions that is required for testing and development.
Boot debugging can be disabled or enabled by using the following commands in WMI or a PowerShell script:
- To disable boot debugging, type **bcdedit.exe /set {current} bootdebug off** - To enable boot debugging, type **bcdedit.exe /set {current} bootdebug on**If BootdebuggingEnabled = 0 (False), then allow access.
If BootDebuggingEnabled = 1 (True), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Place the device in a watch list to monitor the device more closely for potential risks. - Trigger a corrective action, such as enabling VSM using WMI or a PowerShell script. **OSKernelDebuggingEnabled**OSKernelDebuggingEnabled points to a device that is used in development and testing. Devices that are used for test and development typically are less secure: they may run unstable code, or be configured with fewer security restrictions required for testing and development.
If OSKernelDebuggingEnabled = 0 (False), then allow access.
If OSKernelDebuggingEnabled = 1 (True), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Place the device in a watch list to monitor the device more closely for potential risks. - Trigger a corrective action, such as informing the technical support team to contact the owner investigate the issue. **CodeIntegrityEnabled**When code integrity is enabled, code execution is restricted to integrity verified code.
Code integrity is a feature that validates the integrity of a driver or system file each time it is loaded into memory. Code integrity detects whether an unsigned driver or system file is being loaded into the kernel, or whether a system file has been modified by malicious software that is being run by a user account with administrator privileges.
On x64-based versions of the operating system, kernel-mode drivers must be digitally signed.
If CodeIntegrityEnabled = 1 (True), then allow access.
If CodeIntegrityEnabled = 0 (False), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Allow conditional access based on other data points that are present at evaluation time. For example, other attributes on the health certificate, or a device's past activities and trust history. - Take one of the previous actions and additionally place the device in a watch list to monitor the device more closely for potential risks. **TestSigningEnabled**When test signing is enabled, the device does not enforce signature validation during boot, and allows the unsigned drivers (such as unsigned UEFI modules) to load during boot.
Test signing can be disabled or enabled by using the following commands in WMI or a PowerShell script:
- To disable boot debugging, type **bcdedit.exe /set {current} testsigning off** - To enable boot debugging, type **bcdedit.exe /set {current} testsigning on**If TestSigningEnabled = 0 (False), then allow access.
If TestSigningEnabled = 1 (True), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI and MBI assets - Place the device in a watch list to monitor the device more closely for potential risks. - Trigger a corrective action, such as enabling test signing using WMI or a PowerShell script. **SafeMode**Safe mode is a troubleshooting option for Windows that starts your computer in a limited state. Only the basic files and drivers necessary to run Windows are started.
If SafeMode = 0 (False), then allow access.
If SafeMode = 1 (True), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Trigger a corrective action, such as informing the technical support team to contact the owner investigate the issue. **WinPE**Windows pre-installation Environment (Windows PE) is a minimal operating system with limited services that is used to prepare a computer for Windows installation, to copy disk images from a network file server, and to initiate Windows Setup.
If WinPE = 0 (False), then allow access.
If WinPE = 1 (True), then limit access to remote resources that are required for Windows OS installation.
**ELAMDriverLoaded** (Windows Defender)To use this reporting feature, you must disable "Hybrid Resume" on the device. Early launch anti-malware (ELAM) provides protection for the computers in your network when they start up and before third-party drivers initialize.
In the current release, this attribute only monitors/reports if a Microsoft first-party ELAM (Windows Defender) was loaded during initial boot.
If a device is expected to use a third-party antivirus program, ignore the reported state.
If a device is expected to use Windows Defender and ELAMDriverLoaded = 1 (True), then allow access.
If a device is expected to use Windows Defender and ELAMDriverLoaded = 0 (False), then take one of the following actions that align with your enterprise policies, also accounting for whether it is a desktop or mobile device:
- Disallow all access - Disallow access to HBI assets - Trigger a corrective action, such as informing the technical support team to contact the owner investigate the issue. **Bcdedit.exe /set {current} vsmlaunchtype auto**If ELAMDriverLoaded = 1 (True), then allow access.
If ELAMDriverLoaded = 0 (False), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Trigger a corrective action, such as informing the technical support team to contact the owner investigate the issue. **VSMEnabled**Virtual Secure Mode (VSM) is a container that protects high value assets from a compromised kernel. VSM requires about 1 GB of memory – it has enough capability to run the LSA service that is used for all authentication brokering.
VSM can be enabled by using the following command in WMI or a PowerShell script:
bcdedit.exe /set {current} vsmlaunchtype auto
If VSMEnabled = 1 (True), then allow access.
If VSMEnabled = 0 (False), then take one of the following actions that align with your enterprise policies:
- Disallow all access - Disallow access to HBI assets - Trigger a corrective action, such as informing the technical support team to contact the owner investigate the issue **PCRHashAlgorithmID**This attribute is an informational attribute that identifies the HASH algorithm that was used by TPM; no compliance action required.
**BootAppSVN**This attribute identifies the security version number of the Boot Application that was loaded during initial boot on the attested device
If reported BootAppSVN equals an accepted value, then allow access.
If reported BootAppSVN does not equal an accepted value, then take one of the following actions that align with your enterprise policies:
- Disallow all access - Direct the device to an enterprise honeypot, to further monitor the device's activities. **BootManagerSVN**This attribute identifies the security version number of the Boot Manager that was loaded during initial boot on the attested device.
If reported BootManagerSVN equals an accepted value, then allow access.
If reported BootManagerSVN does not equal an accepted value, then take one of the following actions that align with your enterprise policies:
- Disallow all access - Direct the device to an enterprise honeypot, to further monitor the device's activities. **TPMVersion**This attribute identifies the version of the TPM that is running on the attested device.
TPMVersion node provides to replies "1" and "2":
Based on the reply you receive from TPMVersion node:
- If reported TPMVersion equals an accepted value, then allow access. - If reported TPMVersion does not equal an accepted value, then take one of the following actions that align with your enterprise policies: - Disallow all access - Direct the device to an enterprise honeypot, to further monitor the device's activities. **PCR0**The measurement that is captured in PCR[0] typically represents a consistent view of the Host Platform between boot cycles. It contains a measurement of components that are provided by the host platform manufacturer.
Enterprise managers can create an allow list of trusted PCR[0] values, compare the PCR[0] value of the managed devices (the value that is verified and reported by HAS) with the allow list, and then make a trust decision based on the result of the comparison.
If your enterprise does not have a allow list of accepted PCR[0] values, then take no action.
If PCR[0] equals an accepted allow list value, then allow access.
If PCR[0] does not equal any accepted listed value, then take one of the following actions that align with your enterprise policies:
- Disallow all access - Direct the device to an enterprise honeypot, to further monitor the device's activities. **SBCPHash**SBCPHash is the finger print of the Custom Secure Boot Configuration Policy (SBCP) that was loaded during boot in Windows devices, except PCs.
If SBCPHash is not present, or is an accepted allow-listed value, then allow access.
If SBCPHash is present in DHA-Report, and is not an allow-listed value, then take one of the following actions that align with your enterprise policies:
- Disallow all access - Place the device in a watch list to monitor the device more closely for potential risks. **CIPolicy**This attribute indicates the Code Integrity policy that is controlling the security of the boot environment.
If CIPolicy is not present, or is an accepted allow-listed value, then allow access.
If CIPolicy is present and is not an allow-listed value, then take one of the following actions that align with your enterprise policies:
- Disallow all access - Place the device in a watch list to monitor the device more closely for potential risks. **BootRevListInfo**This attribute identifies the Boot Revision List that was loaded during initial boot on the attested device.
If reported BootRevListInfo version equals an accepted value, then allow access.
If reported BootRevListInfo version does not equal an accepted value, then take one of the following actions that align with your enterprise policies:
- Disallow all access - Direct the device to an enterprise honeypot, to further monitor the device's activities. **OSRevListInfo**This attribute identifies the Operating System Revision List that was loaded during initial boot on the attested device.
If reported OSRevListInfo version equals an accepted value, then allow access.
If reported OSRevListInfo version does not equal an accepted value, then take one of the following actions that align with your enterprise policies:
- Disallow all access - Direct the device to an enterprise honeypot, to further monitor the device's activities. **HealthStatusMismatchFlags**HealthStatusMismatchFlags attribute appears if DHA-Service detects an integrity issue (mismatch) in the DHA-Data it receives from device management solutions, for validation.
In case of a detected issue a list of impacted DHA-report elements will be listed under the HealthStatusMismatchFlags attribute.
### **Device HealthAttestation CSP status and error codes**| Error code | Error name | Description |
|---|---|---|
| 0 | HEALTHATTESTATION_CERT_RETRIEVAL_UNINITIALIZED | This is the initial state for devices that have never participated in a DHA-Session. |
| 1 | HEALTHATTESTATION_CERT_RETRIEVAL_REQUESTED | This state signifies that MDM client’s Exec call on the node VerifyHealth has been triggered and now the OS is trying to retrieve DHA-EncBlob from DHA-Server. |
| 2 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED | This state signifies that the device failed to retrieve DHA-EncBlob from DHA-Server. |
| 3 | HEALTHATTESTATION_CERT_RETRIEVAL_COMPLETE | This state signifies that the device has successfully retrieved DHA-EncBlob from the DHA-Server. |
| 4 | HEALTHATTESTATION_CERT_RETRIEVAL_PCR_FAIL | Deprecated in Windows 10, version 1607. |
| 5 | HEALTHATTESTATION_CERT_RETRIEVAL_GETQUOTE_FAIL | DHA-CSP failed to get a claim quote. |
| 6 | HEALTHATTESTATION_CERT_RETRIEVAL_DEVICE_NOT_READY | DHA-CSP failed in opening a handle to Microsoft Platform Crypto Provider. |
| 7 | HEALTHATTESTATION_CERT_RETRIEVAL_WINDOWS_AIK_FAIL | DHA-CSP failed in retrieving Windows AIK |
| 8 | HEALTHATTESTATION_CERT_RETRIEVAL_FROM_WEB_FAIL | Deprecated in Windows 10, version 1607. |
| 9 | HEALTHATTESTATION_CERT_RETRIEVAL_INVALID_TPM_VERSION | Invalid TPM version (TPM version is not 1.2 or 2.0) |
| 10 | HEALTHATTESTATION_CERT_RETRIEVAL_GETNONCE_FAIL | Nonce was not found in the registry. |
| 11 | HEALTHATTESTATION_CERT_RETRIEVAL_GETCORRELATIONID_FAIL | Correlation ID was not found in the registry. |
| 12 | HEALTHATTESTATION_CERT_RETRIEVAL_GETCERT_FAIL | Deprecated in Windows 10, version 1607. |
| 13 | HEALTHATTESTATION_CERT_RETRIEVAL_GETCLAIM_FAIL | Deprecated in Windows 10, version 1607. |
| 14 | HEALTHATTESTATION_CERT_RETRIEVAL_ENCODING_FAIL | Failure in Encoding functions. (Extremely unlikely scenario) |
| 15 | HEALTHATTESTATION_CERT_RETRIEVAL_ENDPOINTOVERRIDE_FAIL | Deprecated in Windows 10, version 1607. |
| 16 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_LOAD_XML | DHA-CSP failed to load the payload it received from DHA-Service |
| 17 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_CORRUPT_XML | DHA-CSP received a corrupted response from DHA-Service. |
| 18 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_EMPTY_XML | DHA-CSP received an empty response from DHA-Service. |
| 19 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_DECRYPT_AES_EK | DHA-CSP failed in decrypting the AES key from the EK challenge. |
| 20 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_DECRYPT_CERT_AES_EK | DHA-CSP failed in decrypting the health cert with the AES key. |
| 21 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_EXPORT_AIKPUB | DHA-CSP failed in exporting the AIK Public Key. |
| 22 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_CREATE_CLAIMAUTHORITYONLY | DHA-CSP failed in trying to create a claim with AIK attestation data. |
| 23 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_APPEND_AIKPUB | DHA-CSP failed in appending the AIK Pub to the request blob. |
| 24 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_APPEND_AIKCERT | DHA-CSP failed in appending the AIK Cert to the request blob. |
| 25 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_INIT_HTTPHANDLE | DHA-CSP failed to obtain a Session handle. |
| 26 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_GETTARGET_HTTPHANDLE | DHA-CSP failed to connect to the DHA-Service. |
| 27 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_CREATE_HTTPHANDLE | DHA-CSP failed to create an HTTP request handle. |
| 28 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_SET_INTERNETOPTION | DHA-CSP failed to set options. |
| 29 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_ADD_REQUESTHEADERS | DHA-CSP failed to add request headers. |
| 30 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_SEND_REQUEST | DHA-CSP failed to send the HTTP request. |
| 31 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_RECEIVE_RESPONSE | DHA-CSP failed to receive a response from the DHA-Service. |
| 32 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_QUERY_HEADERS | DHA-CSP failed to query headers when trying to get HTTP status code. |
| 33 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_EMPTY_RESPONSE | DHA-CSP received an empty response from DHA-Service even though HTTP status was OK. |
| 34 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_MISSING_RESPONSE | DHA-CSP received an empty response along with an HTTP error code from DHA-Service. |
| 35 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_IMPERSONATE_USER | DHA-CSP failed to impersonate user. |
| 36 | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_ACQUIRE_PDCNETWORKACTIVATOR | DHA-CSP failed to acquire the PDC activators that are needed for network communication when the device is in Connected standby mode. |
| 0xFFFF | HEALTHATTESTATION_CERT_RETRIEVAL_FAILED_UNKNOWN | DHA-CSP failed due to an unknown reason, this error is highly unlikely to occur. |
| 400 | Bad_Request_From_Client | DHA-CSP has received a bad (malformed) attestation request. |
| 404 | Endpoint_Not_Reachable | DHA-Service is not reachable by DHA-CSP |