By Thomas Claburn | InformationWeek | May 21, 2010 05:55 PM
"Computer security researchers at the University of Calgary have developed a way to distribute adware without having to convince potential victims to install the adware on their computers."
[. . .]
"What makes the attack interesting is that the user of the contagious computer, like the historical figure Typhoid Mary, is likely to be unaware of his or her role in spreading ads to other computers on the same network. What's more, those receiving the ads won't find any malware on their machines, assuming it's adware rather than malicious software that's being spread."
This is one of those things where the tech is very cool but the use of said tech falls into the realm of very scary. The plus side is that if we know how it is done we can better protect against it. It is similar to why, even though biological warfare weapons are illegal, we still develop them in order to have defensive solutions against them.