the tickets sold by ticket re-sellers may themselves be stolen or counterfeit. For many major sporting events, counterfeit tickets are auctioned off in the months leading up to the event. These criminals and their activities are not to be confused with legitimate ticket brokers and individuals who abide by the law to legally resell tickets on the secondary market. In 2009, Ticketmaster started adoption of a "paperless" restricted ticketing, in which tickets could not be resold. Under this system, customers prove their purchase by showing a credit card and ID. The measure was taken in response to ticket scalping and resale markup of tickets on secondary markets and adopted during Miley Cyrus (2009) World Wonder Tour, although Ticketmaster first experimented it with AC/DC's Black Ice World Tour (2008–10). Ticketmaster has since changed the name of the system to "Credit Card Entry". The system requires large groups to enter together with the person who purchased tickets. Some events have Ticket Transfer which allows the tickets to change ownership and allow for tickets to be transferred through Ticketmaster's proprietary systems. These cannot be later resold or transferred via ticket exchanges such as StubHub. Ticket presales Obtaining tickets through special presales has become more common. These presales often use unique codes specific to an artist's fan club or venue. The advent of presales has allowed more individuals to participate in reselling tickets outside of a brokers office. Although derivatives was a practice in use mostly in the 1980s, some ticket brokers offer tickets even before the tickets are officially available for sale. In such scenarios, those ticket re-sellers are actually selling forward contracts of those tickets. One example is a company called TicketReserve, which is making money by selling "options" on future sporting events. This is often possible if the reseller is a season ticket holder. Season ticket holders generally receive the same exact seat locations year after year thus they can enter a contract to deliver on tickets that they own the rights to, even if those tickets have not even been printed or sent to the original ticket holder. Automated scalping bots In recent years, fraudsters have started to use more complex methods by which they obtain tickets for resale on the secondary market. Similar to the technology used to snatch up rare shoes and sneakers, automated bot attacks have become a common way to acquire large numbers of tickets only