The research from anti-virus firm Panda Software showed an increase compared to the previous quarter, when they accounted for 47 percent of malware detected. At the same time, the number of worms continued to fall, marking less than 5 percent of the total.
The company said the figures confirmed that trojans are being used by criminals for financial gain.
"The trojan is an extremely versatile malicious code, as it can carry out many damaging actions: steal confidential information, take remote control of affected computers, capture keystrokes, etc," said Luis Corrons, director of PandaLabs. "What's more, it is usually installed very discreetly and carries out its actions without the user realising, making it the ideal tool for cyber-criminals. Epidemics caused by mass-mailing worms or by those that exploit software vulnerabilities attract the attention of users, who quickly remove them from their systems. For this reason, they are not suitable for making money easily."
This new aim of malware creators is also reflected in the large number of bots (16 percent) and backdoor trojans (12 percent) detected over the last quarter.
"Although large epidemics seem to have become a thing of the past, the current situation of the internet as regards IT threats is worrying. The amount of new malware is gradually increasing, and most of it is related to cybercrime. This situation causes users to relax, and in many cases, this means that computers are not correctly protected," said Corrons.