Smart Grid addresses the problem of existing powergrid\'s increasing complexity, growing demand and requirement for greater reliability, through two-way communication and automated residential load control among others. These features also makes the Smart Grid a target for a number of cyber attacks. The load profiles of consumers could be changed through the fabrication of price messages. This attack could lead to cascading failures. Our work is the first attempt to study the effect of such cyber attacks on smart grid, seeking the vulnerable critical nodes. With linearized DC power flow model and cascading failure in power grid models, we also provide solutions to mitigate or reduce the damage due to the cascading failures.