Defending against Thermal Covert Channel Attacks by Task Migration in Many-core System

Thermal covert channel (TCC) attack poses severe threat to many-core systems, which leaks sensitive data secretly by using heat transfer as the communication media. There are a few countermeasures that use either dynamic voltage frequency scaling (DVFS) or noise jamming. The DVFS based countermeasure scales the V/F levels down so that the receiver cannot correctly decode the signal. In a noise jamming based countermeasure, a defender core emits thermal noise with the same transmission frequency of the signal to jam the thermal covert channel transmission. However these approaches suffer from degraded system performance or increased power consumption. In this paper, we observed that thermal signal decays fast with respect to the distance between the transmitter and receiver cores/threads in thermal covert channels. Therefore, a task migration based countermeasure is proposed to separate the transmitter and receiver to distant cores such that the thermal covert channel signals decay and the thermal covert channel transmission is blocked. Experimental results show that the packet error rate of thermal covert channels with the proposed countermeasure escalates to 84%, effectively blocking thermal covert channel transmission. Besides, the proposed countermeasure also reduces power consumption by 39.6% and 57.3% compared to two existing countermeasures, and reduces execution time by 68.5% and 42.2% compared to two existing countermeasures. Therefore, the proposed countermeasure is a lightweight but effective defense approach against thermal covert channel.