Troubleshooting the Microsoft OEM Ready Audit Tool: Common Issues & Fixes

Comparing Microsoft OEM Ready Audit Tool Versions: Features & RequirementsThe Microsoft OEM Ready Audit Tool (RAT) is a diagnostic and validation utility designed for Original Equipment Manufacturer (OEM) partners and system builders to verify that devices and their software images comply with Microsoft’s licensing, activation, and platform readiness requirements. Over time Microsoft has released multiple versions of RAT with updates addressing new hardware platforms, Windows feature updates, licensing checks, and telemetry/diagnostic enhancements. This article compares major RAT versions, summarizes key features and system requirements for each, and offers guidance for OEMs choosing which version to use.

Overview: purpose and typical use cases

The OEM Ready Audit Tool is used by OEM partners to:

• Validate Windows activation and licensing configuration on preinstalled systems.
• Verify presence and correctness of required OEM files (OEM certificates, SLP/SLP2 keys where applicable, OEM licensing files).
• Run platform readiness checks (UEFI/GPT, Secure Boot, device drivers compatibility).
• Confirm system meets Windows Hardware Compatibility Program (WHCP) or Windows Hardware Certification requirements where relevant.
• Produce audit reports for internal QA or for submission to Microsoft for validation and support.

RAT versions typically evolve to:

• Support new Windows releases (e.g., major Windows feature updates).
• Add checks for new hardware features (e.g., TPM 2.0, virtualization requirements).
• Update activation/licensing checks in line with Microsoft’s policies.
• Improve reporting format and add integration with OEM provisioning tools.

Major RAT versions — feature and requirement comparison

Detailed feature comparisons

• Activation and Licensing

  • Early versions focused on SLP/COA/BIOS markers used in pre-OEM activation. Later versions moved to validating modern OEM licensing mechanisms, including digital entitlement and online activation flows.
  • Latest RAT versions validate both local activation state and cloud-based activation telemetry and adapt their checks to Microsoft’s current activation APIs.

• Boot and Firmware

  • Early RAT: MBR/BIOS checks only.
  • RAT v2+: Added UEFI/GPT and Secure Boot awareness.
  • RAT v4+ and later: stricter Secure Boot validation, expected UEFI features and firmware versions for Windows 11 compatibility.

• TPM and Hardware Security

  • RAT v3 introduced TPM 2.0 detection and basic ownership checks.
  • RAT v4/v5 added checks for TPM provisioning, attestation, and compatibility with virtualization-based security (VBS), Core Isolation, and Windows Hello for Business.

• Driver and ACPI Checks

  • Progressive improvement in scanning installed drivers and ACPI tables for known issues.
  • Newer RATs include checks targeting driver signing requirements and compatibility with modern power/thermal frameworks, important for certification.

• Reporting and Integration

  • Formats evolved from basic text to XML, CSV, and HTML reports.
  • Latest versions offer structured output suitable for automated ingestion by OEM QA systems and cloud submission for vendor dashboards.

System and software requirements by RAT generation

• RAT v1–v2:

  • OS: Windows 7/8/8.⁄₁₀ (older builds)
  • Firmware: BIOS or early UEFI; MBR or GPT supported depending on build.
  • No TPM requirement.

• RAT v3:

  • OS: Windows 10 (early releases) and Windows Server variants used by OEM labs
  • Firmware: UEFI recommended
  • TPM: detection of TPM 2.0; firmware/factory provisioning considered

• RAT v4:

  • OS: Windows 10 20H2+ and Windows 11 support
  • Firmware: UEFI 2.x+, Secure Boot enabled for full checks
  • TPM 2.0 required for some tests; virtualization extensions recommended

• RAT v5 (current/latest):

  • OS: Windows 10 latest builds and Windows 11 (current servicing)
  • Network: Optional connectivity for cloud reporting and policy checks
  • Firmware: UEFI, Secure Boot; TPM 2.0 for security feature validation
  • Dependencies: Updated Windows SDK components and .NET runtime versions as required by the tool packaging

Choosing the right RAT version for your workflow

• If you build legacy systems targeting BIOS/MBR or older Windows editions, older RAT builds (v1–v2) may be appropriate — but they are no longer suitable for modern certification.
• For mainstream Windows 10 device production with TPM and UEFI, use RAT v3 or v4 depending on which Windows feature set you target.
• For Windows 11 systems or devices intended to ship with modern security features (TPM 2.0, Secure Boot, VBS), use RAT v4 or later.
• If you require integration with cloud provisioning and modern OEM dashboards, choose RAT v5 (or the then-current release) to get cloud reporting and Autopilot/MDM readiness checks.

Migration and compatibility tips

• Always run the RAT version matching the Windows image and firmware target. Running a newer RAT on an older image can produce false failures on checks that the target platform doesn’t need.
• Maintain a lab image that mirrors production firmware settings (Secure Boot on/off, TPM state) so RAT results reflect shipping device behavior.
• Automate RAT runs in your build pipeline and ingest structured output (XML/CSV/JSON) to enforce QA gates.
• Keep the underlying Windows SDK and .NET runtimes updated per RAT release notes to avoid runtime errors.

Common pitfalls and how to avoid them

• False positives from firmware mismatches: verify firmware configuration before audit.
• Outdated drivers or OEM customization interfering with checks: isolate and test a clean reference image.
• Misinterpreting activation states: understand local vs cloud activation — RAT reports typically include both; confirm online connectivity where required.
• Relying on an unsupported RAT: always consult Microsoft partner channels for the supported RAT version for your certification target.

Example audit checklist (short)

• Confirm target Windows version and match RAT version.
• Ensure firmware is set to expected configuration (UEFI, Secure Boot, TPM state).
• Use a clean reference image with signed drivers where possible.
• Run RAT and collect XML/CSV/HTML report.
• Review license/activation, TPM/Secure Boot, driver/ACPI, and Windows feature readiness sections.
• Remediate issues and rerun until clean results.

Conclusion

Microsoft’s OEM Ready Audit Tool has evolved from a simple license/BIOS validator into a sophisticated readiness and security assessment tool aligned with modern Windows and hardware requirements. Selecting the correct RAT version depends on your device’s target Windows release and hardware security posture: use older versions only for legacy targets, RAT v3–v4 for mainstream Windows 10 devices, and RAT v4–v5 for Windows 11 and cloud/MDM-oriented workflows. Follow Microsoft partner guidance and keep your firmware, images, and RAT installation up to date for reliable audit results.