Network on Chip Security - With the advancements in VLSI technology, Tiled Chip Multicore Processors (TCMP) with packet switched Network-on-Chip (NoC) have emerged as the backbone of the modern data intensive parallel multi-core systems. Tight timeto-market and cost constraints have forced chip manufacturers to use third-party IPs in sophisticated TCMP designs. This dependence over third party IPs has instigated security vulnerabilities in inter-tile communication that cannot be detected at manufacturing and testing phases. This includes possibility of having malicious circuits like Hardware Trojans (HT). NoC is the likely target of HT insertion due to its significance and positional advantage from system and communication standpoints. Recent research shows that HTs can manipulate control fields of NoC packets and leads to dead flit attacks that has the potential to disrupt the on-chip communication resulting in application level stalling. In this paper, we propose run time detection of such dead flit attacks by analyzing packet movement behaviours. We also propose a cost effective mitigation mechanism by re-routing the packets around the HT infected router. Our experimental study with real benchmarks on 8x8 mesh TCMP evaluates the effectiveness of the proposed solution.