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Microsoft Introduces Azure Sphere 'Guardian Modules' for Older IoT Devices

• By Kurt Mackie
• March 06, 2019

Microsoft described a new mechanism this week called "Guardian Modules" that enables the use of microcontroller units to secure connections for older Internet of Things (IoT) devices.

Guardian Modules are part of Microsoft's Azure Sphere technology, which is currently in preview. Azure Sphere consists of a chip with processing, memory and security capabilities, plus a Linux-based operating system that Microsoft introduced last year to support IoT devices.

In a typical scenario, an Azure Sphere microcontroller unit connects with the Azure Sphere Security Service. The service adds benefits such as device health-check capabilities and the delivery of automated updates.

It might be thought Azure Sphere microcontroller units would just be used in new or "greenfield" rollouts of IoT devices. However, Microsoft is contending that Azure Sphere can support older "brownfield" IoT deployments, too. It can be done when Azure Sphere microcontroller units serve as Guardian Modules for existing IoT devices. The Guardian Modules can permit older IoT equipment that was disconnected or "air-gapped," possibly for security reasons, to become connected units, adding new value, according to Microsoft's view.

When used as Guardian Modules, Azure Sphere microcontroller units will connect with the Azure Sphere Security Service on behalf of the brownfield IoT device. This arrangement "can protect the equipment from attack, ensure data is only transmitted between trusted cloud and device communications partners, and ensure the software of the module and the equipment remains intact and secured," Microsoft's announcement contended. The brownfield IoT device also can benefit by getting software updates from the Azure Sphere Security Service.

Microsoft's announcement didn't describe when Guardian Modules might be seen, nor when Azure Sphere will be ready for production environments. Guardian Modules, though, seem like a possible solution for a disconnected IoT world of devices.

In other IoT security news, Microsoft this week described co-authoring an "IoT Security Model Practitioner's Guide" (PDF) in conjunction with the Industrial Internet Consortium. The 129-page guide aims "to allow organizations to meet their scenario needs without over-investing in security mechanisms," Microsoft's announcement explained.

The guide isn't prescriptive on the specific security measures to adopt. Instead, organizations go through a process of first identifying an industry profile target they want to reach. Next, they assess their current security maturity state. By comparing between the target state with the current security state, areas where IoT security could be improved get highlighted.

The guide also includes three case studies as examples for improving IoT security. More information about the Security Maturity Model is described in an Industrial Internet Consortium Web presentation, which can be accessed here (requires sign-up).