The Boy-in-the-Browser Attack is a variant of the MitB – Man-in-the-Browser attack involving malware that makes changes to a target machine's routing (often by changing an operating system's hosts file), and subsequently deleting itself.
Such an action allows an attacker to carry out a more traditional MitM Attack in order to steal information sent from a target computer to a particular server, and makes detecting any traces of an initial malware infection extremely difficult.