As botnets go, the Kneber botnet, which has hit about 75,000 PCs in roughly 2,500 companies worldwide, is fairly minuscule. However, it’s disproportionately dangerous because it’s aimed at very specific targets — corporations and government departments — whose PCs store critically important information, such as Social Security numbers and corporate login credentials. The botnet used the ZeuS Trojan, a highly sophisticated piece of malware. It’s also infected about half its victims with a second Trojan, Waledac.