  Only when understanding hackers' tactics, can we thwart their attacks. With
this spirit, this paper studies how hackers can effectively launch the
so-called 'targeted node attacks', in which iterative attacks are staged on a
network, and in each iteration the most important node is removed. In the
existing attacks for weighted networks, the node importance is typically
measured by the centralities related to shortest-path lengths, and the attack
effectiveness is also measured mostly by length-related metrics. However, this
paper argues that flows can better reflect network functioning than
shortest-path lengths for those networks with carrying traffic as the main
functionality. Thus, this paper proposes metrics based on flows for measuring
the node importance and the attack effectiveness, respectively. Our node
importance metrics include three flow-based centralities (flow betweenness,
current-flow betweenness and current-flow closeness), which have not been
proposed for use in the attacks on weighted networks yet. Our attack
effectiveness metric is a new one proposed by us based on average network flow.
Extensive experiments on both artificial and real-world networks show that the
attack methods with our three suggested centralities are more effective than
the existing attack methods when evaluated under our proposed attack
effectiveness metric.
