Design, threat analysis and countermeasures for cache replacement policy-affecting Hardware Trojans in the context of a many-core system

Hardware Trojans, which threaten system reliability and integrity, have emerged as a security threat to the IC industry. Hardware manufacturers acquire ICs from unreliable third parties to reduce time to market and cost. Integration of untrusted component(s) in the IC design cycle and malicious modification(s) of ICs in the design house or foundry is popularly known as the Hardware Trojan. Trojans are implanted within a system to cause system malfunction, destruction or leakage of confidential information. Here, we have designed stealthy Trojans that degrade system performance by intervening in the cache replacement policies of a system. One of the designed Trojans affects systems that use the least recently used (LRU) cache replacement policy and decreases the infected core's HitRatio up to 7.09%. The other one affects systems that use least frequently used (LFU) cache replacement policy and decreases the HitRatio of the infected core up to 8.52%. The proposed mitigation technique can improve the infected core's HitRatio up to 8.19%.