Viruses, spyware, phishing and other scams are conspiring to make the Internet a scary and unsavory place for Joe American, which is a threat to the continued growth of consumer-facing e-commerce efforts.

Gartner, for example, says security concerns could shave a full percentage point off its current forecasts for business-to-consumer e-commerce, which it expects to grow 18% in 2005, 15% in 2006 and 11% in 2007 (see Gartner: Security concerns to stunt e-commerce growth).

Phishing is one of the biggest concerns, Gartner says, with about 1.2 million U.S. consumers suffering phishing-related losses totaling about $929 million between May 2004 and May 2005. (See last week's column for a simple new tool that might help sites fight back)

But spyware is also influencing how consumers use the Internet. According to research released last week by the Pew Internet & American Life Project, "nine out of ten Internet users say they have adjusted their online behavior out of fear of falling victim to software intrusions."

Of the changes the report identified: 48% of the 1,336 people surveyed have stopped visiting particular Web sites; 34% have stopped downloading software; 18% say they no longer open e-mail attachments; and 18% say they have changed browsers to try to avoid surreptitious software installation.

A whopping 43% of the respondents "have had spyware, adware, or both types of programs on their home computer," the report says, surmising the real figure is probably higher given some users don't know if they are infected. The report cites a 2004 study by AOL and the National Cyber Security Alliance, in which half of the respondents said they had spyware/adware on their computers when a subsequent scan of the machines showed 80% were hosting such code.

While the Pew report finds broad understanding of the spyware/adware threat-for example, 78% say they have a good idea what spyware is-it also revealed many users don't know what to do about it: 33% of the respondents say they are not confident in their ability to fight spyware/adware.

Therein lies the real threat to e-commerce: people who know about the threat but don't know how to cope will simply stop using the tool. Companies that are already realizing gains by serving consumers online still have significant work to do in terms of educating customers about how to safely use the Internet.