Do You “Relay” Want to Give Me Away? – Forensic Cues of Smart Relays and Their IoT Companion Apps

As IoT devices become more prevalent in everyday environments, their relevance to digital investigations in- creases. The product class of “smart relays”, which are connected to the low-voltage grid and usually installed in sockets behind walls, has not yet received much attention in the context of smart home forensics. To close a category-specific gap in the device forensics literature, we conducted a multi-device analysis of 16 smart relays from 9 manufacturers, which support six different companion apps in total. Our examination shows that forensic artifacts can be found locally on the smart relays and in the companion app data, as well as remotely on cloud servers of the vendors. Based on our findings, we developed a Python framework to extract forensic artifacts automatically from obtained firmware dumps, from companion app data, and from captured network traffic.