Misleading applications such as fake antivirus scanners (Trojan.FakeAV) or bogus disk defragmenters (UltraDefraggerFraud) are designed to mislead users into thinking that their computer has serious problems that must be fixed by paying for a license of the software. For example, a fake antivirus scanner may perform fake scans of the hard disk and then report multiple non-existent threats. To remove the threats, the misleading application tells the user to purchase a license for the software which may amount to anything from forty to one a hundred dollars plus, depending on whether a "support" package is purchased or not. Of course the software and any support packages offered are bogus and will offer no help whatsoever in cleaning up the problem or protecting against any other threats.
Newer generations of misleading applications may also cause instability on the computer such as moving files around, hiding them, or preventing access to certain resources. This is done to coerce the user into buying the fake software.