Three men that were behind the Mariposa botnet have been arrested by Spanish authorities, according to Computerworld.
In December, a group of volunteers calling itself the Mariposa Working Group disabled Mariposa's command-and-control servers. With the servers now in the working group's hands, the infected computers cannot be misused.
Mariposa was used to steal banking credentials and launch DDoS attacks. It's unclear just how large the botnet is, although The Associated Press puts the number at as many as 12.7 million poisoned PCs. Chris Davis, CEO of Defense Intelligence, says Mariposa infections have been spotted in half of the Fortune 100, as well as hundreds of government agencies.