SentryBus：一种用于I2C传感器接口操作的多视角可观测性模型与验证工具
SentryBus: A Multi-Vantage Observability Model and Validated Instrument for I2C Sensor-Interface Manipulation
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中文总结 AI 辅助
SentryBus为I2C传感器接口操作构建多视角可观测性模型，通过主机侧总线检测操作，经测试可在特定边界内区分操作与合法采集，暂未开展受控攻击试验以确定检测率。
中文摘要 AI 辅助
医疗物联网设备、无人机及网络物理系统中的传感器驱动系统通常会在测量值到达嵌入式处理器后才对其进行信任。位于传感器与处理器之间数字接口上的攻击者可提供合理值，而该值会被正确的固件接受并作为普通遥测数据报告。研究假设：传感器接口操作会在采集路径上留下可观测证据，且该证据会因攻击者所处视角不同而呈现差异，因此被动的主机侧监控器存在可测量的边界，超出该边界后，操作将无法与合法采集区分开来。SentryBus利用事务时序、读写序列、传输长度、地址行为、寄存器及FIFO状态访问，以及原始数据转换来对I2C传感器总线的采集行为进行建模。攻击者被建模为内插式插入器、并行控制器、传感器替换装置或被攻陷的主机，因为商用仅作为目标的传感器无法发起传输，也无法拉伸、重新排序或延迟总线事务。双面测试平台可捕获两条总线、主机内存及遥测数据，检测器仅使用面向主机的总线，其余视角则作为真值。生理实例化报告了三项测量结果：内插式插入器的采集服务时间边界为0.842%，同时保持采集时序和有效载荷内容；遥测视角下的干净采集稳定性持续6304秒，无时钟退化；负结果表明，数据转换特征编码了会话特定的信号统计信息，且不会跨捕获会话传输。工具表征显示，低成本分析器可截断捕获数据而不会产生内核可见错误。受控攻击试验仍待开展，因此暂不声明检测率。
英文摘要
Sensor-driven systems in medical Internet of Things devices, drones, and cyber-physical systems commonly trust a measurement once it reaches the embedded processor. An adversary on the digital interface between sensor and processor can supply a plausible value that correct firmware accepts and reports as ordinary telemetry. The hypothesis is that sensor interface manipulation leaves observable evidence on the acquisition path, that the evidence appears at different vantages depending on attacker position, and that a passive host-side monitor therefore has a measurable boundary beyond which manipulation becomes indistinguishable from legitimate acquisition. SentryBus models acquisition behavior on the I2C sensor bus using transaction timing, read and write sequences, transfer lengths, address behavior, register and FIFO state access, and raw data transitions. The adversary is modeled as an inline interposer, parallel controller, sensor replacement, or compromised host, because a commodity target-only sensor cannot initiate transfers or stretch, reorder, or delay bus transactions. A dual sided testbed captures both busses, host memory, and telemetry, and the detector consumes the host facing bus alone while the remaining vantages serve as ground truth. A physiological instantiation reports three measured results: an inline interposer bounded at 0.842 percent of acquisition service time while preserving acquisition schedule and payload content, clean acquisition stability sustained over 6304 seconds at the telemetry vantage with no clock regression, and a negative result establishing that data-transition features encode session specific signal statistics and do not transfer across capture sessions. Instrument characterization shows that a low-cost analyzer can truncate captures without kernel visible error. Controlled attack trials are still outstanding, so no detection rate is claimed.
