Discovering new vulnerabilities and implementing security and privacy measures are important to protect systems and data against physical attacks. One such vulnerability is impedance, an inherent property of a device that can be exploited to leak information through an unintended side channel, thereby posing significant security and privacy risks. Unlike traditional vulnerabilities, impedance is often overlooked or narrowly explored, as it is typically treated as a fixed value at a specific frequency in research and design endeavors. Moreover, impedance has never been explored as a source of information leakage. This paper demonstrates that the impedance of an embedded device is not constant and directly relates to the programs executed on the device. We define this phenomenon as impedance leakage and use this as a side channel to extract software instructions from protected memory. Our experiment on the ATmega328P microcontroller and the Artix 7 FPGA indicates that the impedance side channel can detect software instructions with 96.1% and 92.6% accuracy, respectively. Furthermore, we explore the dual nature of the impedance side channel, highlighting the potential for beneficial purposes and the associated risk of intellectual property theft. Finally, potential countermeasures that specifically address impedance leakage are discussed.

翻译：发现新型漏洞并实施安全与隐私保护措施，对于保护系统和数据免受物理攻击至关重要。本文揭示了一种名为阻抗的器件固有属性，它可被利用通过非预期侧信道泄露信息，从而构成重大安全与隐私风险。与传统漏洞不同，阻抗特性常被忽视或仅进行局部探究——在研究与设计工作中通常仅将其视为特定频率下的固定值。此外，阻抗从未被作为信息泄露源进行探索。本文证明嵌入式设备的阻抗并非恒定值，且与设备上执行的程序直接相关。我们将此现象定义为阻抗泄露，并利用该侧信道从受保护内存中提取软件指令。在ATmega328P微控制器和Artix 7 FPGA上的实验表明，阻抗侧信道可分别以96.1%和92.6%的准确率检测软件指令。进一步地，本文探讨了阻抗侧信道的双重特性，揭示了其在有益用途和知识产权窃取风险两方面的潜力。最后，讨论了针对阻抗泄露的潜在防御措施。