Phoenix Technologies Ltd.

Kenneth C Taylor

James Leonard Mortensen

Approaches for locally attesting an operational condition of a computer system during powering on the computer system. Prior to an operating system being loaded, an attestation client, executing on a computer system, analyzes a set of resources of the computer system to create measurement data. The attestation client provides the measurement data to an attestation server executing in a secure enclave on the computer system. The attestation server processes the measurement data and provides the processed measurement data to a remediation server. Upon the computer system being determined to be operationally healthy, the remediation server provides an unlock key to a locked persistent storage to permit the computer system to read the operating system stored on the persistent storage. Thereafter, a BIOS on the computer system may read the operating system and permit the same to be loaded on the computer system.

Local oversight and provisioning of BIOS activity

Approaches for securing a host machine against security attacks conducted using Direct Memory Access (DMA). Platform firmware does not enable bus mastering during PCI bus enumeration. When the platform firmware determines that an expansion card has been plugged into an expansion card slot of the host machine, the platform firmware determines whether the expansion card slot has been approved by a user of the host machine for permitting Direct Memory Access (DMA) with the host machine. Unless the expansion card slot has been determined to be approved by the user for permitting Direct Memory Access (DMA) with the host machine, the platform firmware does not allow drivers that might enable DMA to connect to the device and does not grant permission to the expansion card slot and any upstream bridges to conduct Direct Memory Access (DMA) with the host machine.

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Kirkland, WA, United States of America

Kenneth C Taylor