  Social networks help to bond people who share similar interests all over the
world. As a complement, the Facebook "Like" button is an efficient tool that
bonds people with the online information. People click on the "Like" button to
express their fondness of a particular piece of information and in turn tend to
visit webpages with high "Like" count. The important fact of the Like count is
that it reflects the number of actual users who "liked" this information.
However, according to our study, one can easily exploit the defects of the
"Like" button to counterfeit a high "Like" count. We provide a proof-of-concept
implementation of these exploits, and manage to generate 100 fake Likes in 5
minutes with a single account. We also reveal existing counterfeiting
techniques used by some online sellers to achieve unfair advantage for
promoting their products. To address this fake Like problem, we study the
varying patterns of Like count and propose an innovative fake Like detection
method based on clustering. To evaluate the effectiveness of our algorithm, we
collect the Like count history of more than 9,000 websites. Our experiments
successfully uncover 16 suspicious fake Like buyers that show abnormal Like
count increase patterns.
