rogue dialler

noun

a dial-up connection placed on a computer without the user's knowledge which, when the user tries to connect to the internet, automatically connects to a premium-rate phone number

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012