Secure Hardware Bus Filtering Unsafe Packets

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Solution Overview

Problem

Unprotected hardware buses pose a security risk by allowing unsafe data packets to be communicated from untrusted computing devices to host computing devices, potentially leading to privilege escalation, unauthorized access, or system faults, especially in virtual machine environments where multiple operating systems share resources.

Innovation Solution

A secure hardware bus is introduced between the host computing device and the unprotected hardware bus, featuring a bridge with a bus computing device that processes data packets using a library or formula to determine safety, allowing safe packets to pass through while denying unsafe ones, thus preventing system reboots and maintaining security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an unprotected hardware bus is used for communication between host computing device and peripheral computing devices, then device complexity is reduced and ease of operation is improved, but security reliability deteriorates due to vulnerability to unsafe data packets

Engineering Contradiction:
Improvesecurity reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A secure bridge device is introduced as an intermediary between the unprotected hardware bus and the host computing device. This bridge receives data packets from the unprotected bus, analyzes them for safety using a library of unsafe packet characteristics, and only forwards safe packets to the host. This intermediary structure protects the host from unsafe packets while maintaining compatibility with existing unprotected bus infrastructure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The communication path is segmented into three distinct segments: the unprotected hardware bus, the secure bridge device, and the host computing device. This segmentation isolates the host from direct exposure to unsafe packets on the unprotected bus, allowing security validation to occur in the intermediate bridge segment without affecting the overall system operation.

Inventive Principle:
Principle #1Segmentation

2Reliability

If a secure hardware bus with bridge is introduced to filter unsafe data packets, then security reliability is improved, but device complexity increases due to additional filtering components

Engineering Contradiction:
Improvesecurity reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The secure bridge acts as a mediator that implements security filtering functionality. It contains a processor that executes safety analysis algorithms and a library of unsafe packet characteristics, providing comprehensive security validation without requiring modification of the host computing device or the unprotected bus infrastructure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

Safety analysis is performed in advance before data packets are forwarded to the host computing device. The bridge device pre-validates all incoming packets by comparing them against the library of unsafe packet characteristics, ensuring that only pre-cleared safe packets reach the host, thereby preventing security incidents before they can occur.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If all data packets are validated for safety before delivery to host computing device, then security reliability is improved, but processing time increases due to validation overhead

Engineering Contradiction:
Improvesecurity reliabilityVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The bridge device performs partial validation by checking only specific characteristics of data packets against the library of unsafe packet patterns. Rather than进行全面 analysis of every packet, the system focuses on identifying known unsafe patterns, which provides adequate security protection while minimizing validation time and processing overhead.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The library of unsafe packet characteristics is pre-computed and stored in the bridge device, allowing for rapid pattern matching during packet validation. This preliminary preparation of security criteria enables fast validation decisions without requiring complex real-time analysis, thereby reducing processing time while maintaining security effectiveness.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3566170B1Securing an unprotected hardware bus
Publication Date: 2020.11.18 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3566170B1 patent drawingFigure 1
  • EP3566170B1 patent drawingFigure 2
  • EP3566170B1 patent drawingFigure 3

AI summary

Techniques are disclosed for securing communication from an unprotected hardware bus. The described techniques may be implemented by placing a secure hardware bus between the unprotected hardware bus and a host computing device. The secure hardware bus acts as a filter to prevent delivery of unsafe data packets to the host computing device. The filtering may be particularly useful for preventing delivery of a data packet that would trigger a reboot of the host computing device.