Malicious users are beginning to abandon the use of infected computers for zombie networks and data theft, according to a report by Kaspersky Lab.
Malicious malware authors are instead employing blackmail schemes, where users are told they should send a specific amount of ransom money to the malicious users.
"The ransom demanded varies significantly depending on the amount of money available to the victim. We know of cases where the malicious users have demanded $50, and of cases where they have demanded more than $2,000," according to the Kaspersky report. "The first such blackmail case was in 1989, and now this method is again gaining in popularity."
The GpCode and Krotten trojans were cited by Kaspersky as examples of this type of activity. The lab saw two dozen variants of GpCode.
Kaspersky also noted an increase in malware infections of mobile devices. Company researchers add ten new trojans for smartphones to its databases every week, many of which are written in South Korea, according to the report.
An increasing number of viruses for Apple's Macintosh operating system also was noted in the report. The recent announcement that new versions of Mac would run on Intel processors gained the attention of malware authors, according to the report.
"Until the announcement was made, personal computers had been a field of battle between Windows and Linux-based platforms," according to the report. "The possibility of using MacOS was of interest to a great many people. The potential popularity and consistent growth of future versions of MacOS didn't just attract the attention of IT professionals and users, but naturally also of virus writers and hackers around the world."
Shane Coursen, senior technology consultant at Kaspersky, also noted the increased use of rootkit technology by malicious users in 2006.
"You should expect to see more of those kinds of things," he said. "In the next three to five years, you're going to continue to see more complicated ways of attacking things."