In this episode of “You Gotta Hack That,” Felix explores the world of occupancy sensors, focusing on their role in the security of the Internet of Things (IoT). These sensors play a critical role in modern systems, detecting the presence of people and influencing various actions like security alarms, HVAC systems, and lighting. Occupancy sensors come in different types, each with varying levels of complexity. At the top end, there are complex sensors like noise and video sensors, which require sophisticated computation to interpret the data they receive accurately.

The discussion centers around Passive Infrared Sensors (PIRs), which are commonly used but not well-understood by the general public. PIRs detect changes in infrared radiation in their environment, typically using pyroelectric components. These components change resistance when exposed to infrared radiation, creating a detectable signal. A key feature of PIRs is the use of Fresnel lenses to focus infrared radiation and enhance sensor sensitivity. The lenses include multiple offset circles, broadening the sensor’s detection range, akin to a fly’s compound eye.

Felix explores potential vulnerabilities in PIRs. One method to manipulate them is by blocking infrared radiation using materials like glass plates, rendering the sensor ineffective. Saturation of the sensor through controlled temperature changes is another approach, albeit slower. He recalls personal experiments where moving extremely slowly in front of a PIR could potentially evade detection due to the sensor’s sensitivity limitations. Moreover, attackers could tamper with communication mechanisms or manipulate sensor data, leading to compromised systems relying on garbage data.

Felix emphasizes that while sensors are integral to various urban systems, their data should be treated with caution and verified. The principle of “trust but verify” applies, where sensor cybersecurity requires careful consideration. To bolster security, Felix suggests combining multiple sensors or incorporating redundancy in the system to address faults and failures effectively. He concludes by inviting listeners to engage with the show, share feedback, and explore the critical role of IoT sensor security in our increasingly connected world.