Advance fee fraud, typically claiming that the victim will receive an actually non-existent lottery prize, government grant or loan, 10 years of computer and anti-virus support, compensation for a car accident, etc.
Securities fraud, often via boiler rooms: calling people believed to be gullible and selling worthless securities, and sometimes fraudulently offering, for payment, to recover money lost to a boiler room fraud (in itself an advance fee fraud). The same mechanism is used to sell timeshared holiday accommodation not worth the price asked, then charging a fee to apparently help the customer to sell on the timeshare. In this type of fraud amounts are potentially large, and there is often the appearance of a legitimate company, with Web site and so on.
Overpayment fraud, where a payment is due to the victim, typically for an online auction sale or classified advertising, and a check or money order for a larger amount is sent with some pretext, with a request to send the goods and also wire back the "overpaid" amount; the check is fraudulent, and both goods and money sent are lost.
Cramming (small charges are added to a bill by a third party without the subscriber's consent or disclosure)
Misrepresented office supplies or directory listing services. These typically seek information for use in attempts to bill for unsolicited products and services (such as the model number of office equipment, for which a fraudulent vendor ships an unsolicited order of toner at an inflated price).
A telephone call is made saying typically that virus activity has been detected on the victim's computer; calls may claim to be associated with a reputable company such as Microsoft. Callers assume that the victim has a computer running a Microsoft Windowsoperating system (users of other operating systems, such as Linux, are a minority, and likely to be technically knowledgeable). They ask users to take actions which display information which looks alarming and unexpected, although in fact perfectly normal, such as the Windows event viewer log or temporary files list, and say that it is evidence of infection. Victims are often directed to a remote desktop software website such as ammyy.com; the caller then has complete control over the computer, and can display further alarming displays, and install malware. An offer may be made to remove the "viruses" and supply remote computer support for several years for a single payment. The U.S. Federal Trade Commission has filed lawsuits against a number of businesses and websites performing this scam. If malware is installed on a computer by any means including this, an attacker can have continuing full control, and access to sensitive personal, financial, or business information, until the malware is reliably removed. See also Rogue security software.