The US Department of justice said it has arrested 10 people from Bosnia and Herzegovina, Croatia, Macedonia, New Zealand, Peru, the United Kingdom, and the United States related to the operation of the butterfly (mariposa) botnet.
The exact infection rate can't be ascertained with certainty however it is believed over 11 millions systems are infected worldwide. As one of the biggest and most widely known botnets, experts estimate that it stole close to $850M by harvesting financial information from 800,000 people.
Facebook becomes the tool
You can read the FBI statement here, however the most interesting part of the story is this:
"Facebook’s security team provided assistance to law enforcement throughout the investigation by helping to identify the root cause, the perpetrators, and those affected by the malware. Yahos targeted Facebook users from 2010 to October 2012, and security systems were able to detect affected accounts and provide tools to remove these threats."
Cybercrime is on the rise
Criminals follow the money and right now, the money is moving online. As more of the world's financial transactions happen on the internet, more of the world's criminals gravitate to online crime. These nefarious individuals will use any means available to reach their goals and unfortunately most of the time, it involved tricking you to infect your machine then steal your information (banking, financial, corporate information, intellectual property, etc).