The use of password-stealing trojans has jumped some 400 per cent in the past year, according to a recent report from McAfee.

The security firm said that in 2008, nearly 400,000 variants on trojans designed to log keystrokes and record passwords were found. By comparison, fewer than 100,000 such samples were detected in 2007.

Not only is the malware becoming more numerous but, according to McAfee, data-stealing techniques have also become more sophisticated.

The company noted that many malware programs now attempt to disable security software and access data directly from system files. Additionally, the transmission of the stolen data has become more secure and the destinations harder to track.

McAfee suggested that much of the increase had to do with the rising use of online gaming and the e-commerce markets that have sprung up alongside many popular online multiplayer games.

"Whereas infections with password stealers targeting games were seen less commonly before, 2006 and 2007 have seen an increase in this subcategory, too," the company noted in the report.

"During that period, underground economies have sprung up around the trade of virtual game goods, like swords, helmets, and skill points."

Gamers, however, are not the only targets for the rising tide of password-stealing malware. With the aid of more sophisticated techniques and the use of so-called 'money mules,' theft of bank account details has also risen.

The company found that the issue was further complicated because financial institutions are adding more layers of security and in some cases adding to confusion among users.

"The evolution of password-stealing malware is driven by a cops-and-robbers game between cybercriminals and online banking institutions," read the report.

"But implementing more security doesn’t necessarily bring about better usability."