"These are sophisticated folks who know how to hide themselves on the Internet," John Brown, a section chief with the FBI who oversees operations in the agency's cyber division, said of Perez-Melara and creators of other "hacking-for-hire" services.
In one case earlier this year, a New York police detective was arrested for spending more than $4,000 on hacking services to obtain the emails of more than a dozen of his colleagues. Many of the operators tend to be based overseas.
The case of Perez-Melara, 33, is noteworthy because he appears to have made relatively little money on the scheme, unlike others on the FBI list who were accused of bilking millions of dollars from businesses and Internet users worldwide. But Perez-Melara, a native of El Salvador who was in the United States on a student visa in 2003 when he sold the spyware, allegedly helped turn average computer users into sophisticated hackers who could stalk their victims.
Loverspy was designed "with stealth in mind, claiming that it would be impossible to detect by 99.9 percent of users," according to a July 2005 federal indictment of Perez-Melara.
Brown said Perez-Melara was added to the FBI most wanted list in part because the former college student has been so difficult to find. The government is now offering a $50,000 reward for information leading to his arrest.
According to his indictment, Perez-Melara sold the software to 1,000 customers, who then tried to infect about 2,000 others. Victims took the bait only about half the time, the government said. People who purchased the spyware were charged with illegally intercepting electronic communications. Most of those cases appear to have resulted in probation and fines.
In addition to hacking-for-hire services, there is an established commercial market for snooping software that domestic violence advocates warn can also be used to stalk victims. Software such as ePhoneTracker and WebWatcher, for example, are advertised as ways to monitor kids' online messages and track their location. For $349 a year, Flexispy of Wilmington, Del., promises to capture every Facebook message, email, text and photo sent from a phone, as well as record phone calls. These services generally would be legal only if the person installing the software also owned the device or were given consent by the owner.
Others identified on the FBI most wanted cyber list includes Alexsey Belan, a Russian, who allegedly broke into the computer networks of three major U.S. e-commerce companies. Belan is accused of stealing the companies' user databases and encrypted passwords, which he then sold. Two others named by the FBI hijacked computers with malware disguised as online advertisements, then sold security fixes to victims. In one case, the loss to consumers was estimated to be $100 million.