document: Detectives : detecting coalition hit inflation attacks in advertising networks streams Click fraud is jeopardizing the industry of Internet advertising . Internet advertising is crucial for the thriving of the entire Internet , since it allows producers to advertise their products , and hence contributes to the well being of e-commerce . Moreover , advertising supports the intellectual value of the Internet by covering the running expenses of publishing content . Some content publishers are dishonest , and use automation to generate traffic to defraud the advertisers . Similarly , some advertisers automate clicks on the advertisements of their competitors to deplete their competitors ' advertising budgets . This paper describes the advertising network model , and focuses on the most sophisticated type of fraud , which involves coalitions among fraudsters . We build on several published theoretical results to devise the Similarity-Seeker algorithm that discovers coalitions made by pairs of fraudsters . We then generalize the solution to coalitions of arbitrary sizes . Before deploying our system on a real network , we conducted comprehensive experiments on data samples for proof of concept . The results were very accurate . We detected several coalitions , formed using various techniques , and spanning numerous sites . This reveals the generality of our model and approach .
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