Sixty percent of U.S. businesses polled in a recent national survey plan to increase spending on computer security systems in the months ahead. Worries about computer sabotage are generating increased business for U.S. network security firms.

Guarded Networks and Digital Defense are companies that have specialized in helping financial firms, such as banks and credit unions, protect themselves against unauthorized cyber intrusions.

Both are now expanding to meet demands in new areas, such as local governments, medicine and public utilities.

Guarded Network's president, Richard Dobrow says the September 11 terrorist attacks made all businesses re-examine their potential vulnerability to cyber attacks. "There's really an endless amount of thoughts on how someone could disrupt infrastructure, if they wanted to. If a utility company were attacked through the Internet, and access was gained to some core systems, for example, energy could be disrupted. The threat is fairly broad," he said.

Digital Defense's Marc Enger adds, although there is no evidence of a concerted attack by any nation on U.S. businesses, there are other places in the world where cyber attacks are going on. "I would point out that there has been extensive cyber warfare carried out between the Pakistanis and the Indians, between Taiwan and China, and between the Israelis and the Palestinians. The issue isn't whether it can happen. It is happening," he said.

Marc Enger stresses preventive security. He urges his clients to keep their systems updated with the latest anti virus protections and firewalls, which can seal off data from outside intrusion. "Know where your most important information is, and make sure that is what you are trying to protect first and foremost. Second, always make sure that you are running back-ups, and that you have back-up contingency plans available, in the event that you lose your networks," he said.

Richard Dobrow also recommends system monitors that detect suspicious behavior. "On a 24 hour basis, technologies will track the traffic patterns of activity, and identify where users are coming from, and when that activity looks suspicious. And in those cases, issues are brought to closure through investigation," he said.

New inventions are on the horizon, Richard Dobrow predicts. He says heightened demand is pushing vendors to create new types of protective hardware and software.