A Passive Network Storage Covert Channel for Internet of Things

Network covert channels in the Internet of Things (IoT) can conceal device communication behaviors, thereby protecting user privacy and ensuring secure transmission of sensitive data. However, existing active covert channels in IoT are constrained by the low computational power and limited storage of IoT terminal devices, making them unsuitable for complex steganographic algorithms. Moreover, the active covert channel is more vulnerable to targeted detection and blocking by traffic analysis. To address these challenges, this study proposes a passive network storage covert channel (PNSCC) that leverages intermediate IoT nodes. We also present solutions for synchronization and reversible data hiding within the PNSCC. A covert channel kernel module was designed and deployed on smart routers running the OpenWrt system, followed by experimental testing. The results indicate that the PNSCC achieves a relatively high capacity, with a covert data transmission rate of approximately 88.97 bps in real-world network environments. Additionally, it has minimal impact on actual network performance and exhibits resilience against traffic analysis.