In an alert sent recently to the center's members, the industry group indicated that "in the past six months, financial institutions, security companies, the media and law enforcement agencies are all reporting a significant increase in funds transfer fraud involving the exploitation of valid banking credentials belonging to small- and medium-sized businesses."

The attacks are believed to originate from organized "cyber-gangs" in Eastern Europe, the alert noted.

The cyber-gangs typically send an email to the SMB's controller or treasurer, prompting them to open a link which installs a password-stealing virus. After getting access to the company's financial information through this password, the hackers then initiate a series of wire transfers, the Washington Post reported.

Small businesses are more vulnerable than consumers when it comes to online fraud, as consumers have 60 days to notice and dispute fraudulent charges, while businesses only have two days, said Amit Klein, CTO of Trusteer Security Research Group.

Small businesses are encouraged to make sure their security software and firewalls are all up to date, and to carefully monitor their balance sheets, Klein advised.