  Backdoor attacks in the traditional graph neural networks (GNNs) field are
easily detectable due to the dilemma of confusing labels. To explore the
backdoor vulnerability of GNNs and create a more stealthy backdoor attack
method, a clean-label graph backdoor attack method(CGBA) in the node
classification task is proposed in this paper. Differently from existing
backdoor attack methods, CGBA requires neither modification of node labels nor
graph structure. Specifically, to solve the problem of inconsistency between
the contents and labels of the samples, CGBA selects poisoning samples in a
specific target class and uses the label of sample as the target label (i.e.,
clean-label) after injecting triggers into the target samples. To guarantee the
similarity of neighboring nodes, the raw features of the nodes are elaborately
picked as triggers to further improve the concealment of the triggers.
Extensive experiments results show the effectiveness of our method. When the
poisoning rate is 0.04, CGBA can achieve an average attack success rate of
87.8%, 98.9%, 89.1%, and 98.5%, respectively.
