The number of bots released in 2005 was almost triple that of the year before, Madrid-based Panda Software, spotlighting the growing problem of PC hijacking. That’s not surprising, considering the large number of variations attackers crank out for some bot families. The Gaobot clan (also dubbed “Agobot”) alone spun off more than 6,000 variants last year. Botnets, which are typically controlled by a “herder,” or handler, can be composed of thousands, or hundreds of thousands, of contaminated PCs.