Since its inception some six years ago, the Cutwail / Pandex botnet experienced its fair share of setbacks, but it’s still going strong. The main reason for its existence is to send out millions of spam messages per day, and it occasionally also harvests information such as email addresses in order to include them in new spam campaigns. As the Virut botnet a week ago, this most resilient of botnets has recently been rented by cyber crooks wishing to infect computers with malware – in this case, the backdoor Cridex worm.