The ad fraud network #Methbot explained in a recent report by White Ops.
The excellent report :
▻http://go.whiteops.com/rs/179-SQE-823/images/WO_Methbot_Operation_WP.pdf
A good summary :
▻https://krebsonsecurity.com/2016/12/report-3-5m-in-ad-fraud-daily-from-methbot
The raw data (IP addresses, domain names, etc) :
▻http://www.whiteops.com/METHBOT