thiefware

Slang for when a company seizes revenues of online merchants and affiliates by siphoning commissions. 

To monitor how people arrive at a certain Web site, a tracking link is attached to the shopper's browser in order to make sure the affiliate receives payment.  A company who engages in "thiefware" is potentially hijacking customers from other sites and that falls under spyware.  In e-commerce, it is not unusual for online merchants to pay a small referral fee to Web sites that generate leads, but stealing is something else.