Spanish authorities announced this week that they shut down what appears to be the largest botnet ever discovered. The Mariposa botnet, which first appeared in 2008, was a network of nearly 13 million virus-infected PCs, remotely operated by thieves stealing private information from computers in half the Fortune 1000 companies and 190 countries. Though three men are now in custody, worries over the bot are far from over. Juan Salon at the Spanish Civil Guard was relieved to catch the three men, aged between 25 and 31, whose names have not yet been released. But the guard was troubled to find that none of the three possessed the technical know-how to design something like the Mariposa.