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27.1 Ensure 'Device Enumeration Policy' is set to 'Block all (most restrictive)'

Information

This policy is intended to provide additional security against external DMA-capable devices. It allows for more control over the enumeration of external DMA-capable devices that are not compatible with DMA Remapping/device memory isolation and sandboxing.

The recommended state for this setting is: Block all (most restrictive).

Note : This policy does not apply to 1394, PCMCIA or ExpressCard devices. The protection also only applies to Windows 10 R1803 or higher and requires a UEFI BIOS to function.

Note #2 : More information on this feature is available at this link: Kernel DMA Protection for Thunderbolt(TM) 3 (Windows 10) | Microsoft Docs https://docs.microsoft.com/en-us/windows/security/information-protection/kernel-dma-protection-for-thunderbolt.

Device memory sandboxing allows the OS to leverage the I/O Memory Management Unit (IOMMU) of a device to block unpermitted I/O, or memory access, by the peripheral.

Solution

To establish the recommended configuration via configuration profiles, set the following Settings Catalog path to Block all (most restrictive).

Dma Guard\Device Enumeration Policy

Impact:

External devices that are not compatible with DMA-remapping will not be enumerated and will not function unless/until the user has logged in successfully and has an unlocked user session. Once enumerated, these devices will continue to function, regardless of the state of the session. Devices that are compatible with DMA-remapping will be enumerated immediately, with their device memory isolated.

Warning: Windows Autopilot - Policy Conflicts https://learn.microsoft.com/en-us/autopilot/policy-conflicts: Windows Autopilot pre-provisioning doesn't work when this policy setting is configured.

If Windows Autopilot is used in the environment, assign this setting exclusively to user groups rather than device groups. This ensures the setting is applied later during enrollment, allowing Windows Autopilot to complete its pre-provisioning process and prevent potential interruptions.

See Also

https://workbench.cisecurity.org/benchmarks/27291

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-8, CSCv7|1.4

Plugin: Windows

Control ID: 27fbf3323e40eee46b4f8ac313d1f77e8c40a5b478f5b46799a1ceb5dbf48076