Symantec found that the Web sites of almost all of the survey participants showed traces of activity from the type of software scanners used by hackers.
Aled Miles, the European managing director of Symantec, said: "The scary statistic is that 95% of those who took part were visited by an automated or individual hacker trying to find out if there was an open port, or trojan, present that could be used to launch remote Web attacks or steal confidential information.
"There were a number of cases of hackers trying to put a trojan into the user's system."
Miles added that the findings banished the notion that it was just large corporations which were likely to come under attack from malicious hackers. "Just because you are a small business user with no public persona, that doesn't mean to say that you are not going to be intruded upon, due to the fact that the majority of attacks are automated," he said.
Miles also expressed his alarm at the low level of company awareness regarding hacking, but said there were a variety of things which companies could do to lessen the problem. "A personal firewall is a very effective method of security for the small business user, but other things, such as being careful with e-mail and turning off file-sharing, are also effective," he said.