Because malicious hackers exploit a flaw in the way the Windows handles animated cursors to steal your login info and rape your account:

The flaw came to light in late March and lets attackers take over vulnerable PCs via booby-trapped websites. Warcraft players seem to be one of the targets because accounts for the game are potentially worth significant sums of money.

But the really interesting part is that the hack isn’t directly related to Warcraft. Instead, they’re using it gather WoW login info rather than credit card info because “the raw value of a WoW account is now higher than a credit card and its associated verification data.” How crazy is that?