Businesses in North America and Europe remain broadly worried about the security of open-source software, according to new data from Forrester Research.

Fifty-eight percent of the large companies surveyed said they had security concerns about open source, while the figure for small and midsized businesses was slightly higher, at about two-thirds. Within those groups, only 9 percent of enterprises said they were "very concerned," compared with 45 percent for the SMBs.

More than half of SMBs (57 percent) also expressed concern that open-source software would be complex and hard to adopt, but only 32 percent of enterprises expressed a similar sentiment. In addition, 68 percent of SMBs cited the availability of service and support for open-source software as a concern, compared with 47 percent of enterprises.

The findings are among a wide range of data Forrester collected for two reports, "The State of SMB Software: 2009" and "The State of Enterprise Software: 2009."

Meanwhile, security concerns over SaaS (software as a service) seem to be diminishing among companies large and small, according to Forrester.

The research firm polled a subset of SMB respondents who indicated they weren't interested in SaaS. Twenty-seven percent named security as a factor, compared to 57 percent in a 2007 survey. A similar poll of enterprises saw 31 percent cite security concerns with SaaS, down from 47 percent in an earlier study.

Overall, Forrester polled 2,227 IT executives and technology decision makers in the U.S., Canada, Germany, France and the UK between December 2008 and February this year.