Stealware refers to a type of malware that covertly transfers money or data^[1] to a third party.

Specifically, stealware uses an HTTP cookie to redirect the commission ordinarily earned by the site for referring users to another site.

The term “Stealware” falls under the category of Spyware. Spyware are software applications that collect information about users without their permission instead of directly harming devices.^[2] Both of these terms, in the broader classification, fall under the category of Malware.^[3] Due to their broad definitions, Spyware and Malware both refer to a lot of different types of Malicious Software and in the more niche sense, stealware is any type of malicious software that "redirects the payment of affiliate marketing revenues from the legitimate affiliate to the spyware vendor by placing the spyware operator's affiliate tag on the user's activity or replacing any other tag, if there is one."^[2] The niche aspect of the term stealware makes it a less known and rarely used term. Hence, it is more generalized as a type of spyware in mainstream usage.

Stealware has also broadened its capabilities through the manipulation of online banking systems. In a more mainstream term, this is known as banking malware. This malicious software manipulates online banking transactions and launders the stolen money to the operator of the malware.^[4]