This is according to new research from security company PandaLabs, which found that there has been a 600 per cent increase in the amount of computers that are vulnerable to such software.
Most of these (71 per cent) are Trojans, which are written by hackers to obtain confidential financial data that is then sold on the black market for around $4 per account.
"One of the possible reasons for this increase is the economic crisis," technical director of PandaLabs Luis Corrons explained.
He added that social networks are playing an increasingly major role in the "distribution and infection" of malware.
One such company to be hit by a hacking attack is hotel chain Radisson, which this week said credit card details were stolen from some of its computer systems between November 2008 and May 2009.
Written by Claire Archer