In this paper, we study stealthy false-data attacks that exploit the vulnerabilities of power budgeting scheme in NoC, which can cause catastrophic denial of service (DoS) effects. Essentially, when a power budget request packet is routed through a Trojan-infected network-on-chip node's router, the power budget request can be unknowingly modified. The global manager then tends to make really bad power budget allocation decisions with all the tampered power requests it received. That is, legitimate applications will be victimized with lower power budgets than what they initially asked for, and thus, could suffer serious performance degradation; malicious applications, on the other hand, may be entitled to high power budgets and thus see performance boost that they do not deserve. Our study has shown that this new type of DoS attack can be initiated and sustained by a simple hardware Trojan (HT) circuit that is extremely hard to be detected. The effects of this new DoS attack are simulated using a network model, and all the major parameters and factors that impact the attack effects are identified and quantified.