The Des Moines Register reports that an information security officer used malicious code to manipulate lottery results in Wisconsin, Colorado and Oklahoma.

Apparently

Examiners found out-of-place programs known as dynamic link libraries, or DLLs, that had been written onto the Wisconsin computer. The programs were designed to “redirect” a drawing if certain conditions were met…

This is a problem with applications that use common libraries (such as DLLs). It’s difficult to be sure what code is being executed.