Wireless sensor networks become popular at the start of this millennium due to presence of small-sized sensors with low power deployed for monitoring large area. There is large amount of research being done to increase life of these networks, where lifetime of network is measured from time of deployment to the time when one of the nodes becomes in-operational as power supply is completely used up by the node. It is commonly known as first node failure. In this paper, the authors have discussed the effect of attacks on routing protocols which are designed to be secured. These attacks are known as vampire attacks and they can permanently disable the network by using all the battery power of different nodes.