A botnet that was believed to have illegally infected somewhere between 300,000 and 8 million machines and was raking in an estimated $1 million a year has been shut down by security experts. The Bamital botnet was shut down when teams working with Microsoft and Symantec anti-virus specialists raided several data centres in the US. Microsoft and Symantec claim that the computers infected by the Bamital botnet were being used illegally for identity theft. Thousands of affected users have been offered free tools to help to clean up infected machines.