A series of web sites are pushing a scam promising $5-30 worth of free bitcoins a day simply by running their Bitcoin Collector program. In reality, this program does nothing but install ransomware or password-stealing Trojans onto a victim’s computer. The scam was first discovered by a malware researcher going by the alias Frost who posted about it on Twitter and discussed it with BleepingComputer.com. The scam is promoted through sites that promise to earn you Bitcoin by referring other people to their site. Their FAQ states that by referring 1,000 visits using your referral link you will earn 3.
Source: https://www.bleepingcomputer.com/news/security/new-bitcoin-scam-leads-to-ransomware-and-info-stealing-trojans/