  Cryptocurrencies represent one of the most attractive markets for financial
speculation. As a consequence, they have attracted unprecedented attention on
social media. Besides genuine discussions and legitimate investment
initiatives, several deceptive activities have flourished. In this work, we
chart the online cryptocurrency landscape across multiple platforms. To reach
our goal, we collected a large dataset, composed of more than 50M messages
published by almost 7M users on Twitter, Telegram and Discord, over three
months. We performed bot detection on Twitter accounts sharing invite links to
Telegram and Discord channels, and we discovered that more than 56% of them
were bots or suspended accounts. Then, we applied topic modeling techniques to
Telegram and Discord messages, unveiling two different deception schemes -
"pump-and-dump" and "Ponzi" - and identifying the channels involved in these
frauds. Whereas on Discord we found a negligible level of deception, on
Telegram we retrieved 296 channels involved in pump-and-dump and 432 involved
in Ponzi schemes, accounting for a striking 20% of the total. Moreover, we
observed that 93% of the invite links shared by Twitter bots point to Telegram
pump-and-dump channels, shedding light on a little-known social bot activity.
Charting the landscape of online cryptocurrency manipulation can inform
actionable policies to fight such abuse.
