Here's one more thing for customers to fear. Will it affect your marketing? (Part one of two.)

It's Troy, 1250 BC. After 10 years of siege, a dejected Greek army sails away from the city, leaving a monolithic parting gift. The Trojans, about to look that gift horse in the mouth, are convinced to lead the mighty equine through the city gates by the spy Sinon, who guarantees that the magnificent stallion will make Troy invincible. While the unsuspecting victims sleep, Sinon opens a secret compartment beneath the horse, and out crawl armed troops who, along with the returning Greek army, crash the city and burn it to the ground.

Diabolically clever then, and -- hold your horses -- now.

Although 3,254 years have past, one fundamental strategy has survived to breach the walled sanctuary of your home or office computer -- the seemingly innocent invitation for you to be the instrument of your own demise.

The evolution of online marketing has opened the backdoor to a far more sinister threat. Riding in on the gift horses of freeware, shareware, adware, chat rooms, instant messaging and exciting-but-questionable Web sites, meet the Trojan Horse, New Millennium Edition. It's one more thing for Internet-wary consumers to fear, which could fan the flames for consumers who haven't yet accepted the safety of online buying.

And because you also are a consumer, this is a lesson in ancient history, so that you will not be condemned to repeat it. This is a dire warning: Be afraid. Be very afraid.

Beyond a virus

While viruses and spyware are annoying, infuriating and potentially damaging, Trojan Horses not only may saddle you with unauthorized credit card purchases and lassoed bank accounts, they also could horsewhip you with criminal complicity; a fact of which you could be, right now, totally and blissfully unaware. Until, that is, there is a knock at your door from the FBI, announcing that you are under arrest for suspicion of distributing illegal images. The devastating truths about Trojans go far beyond the simple evils of stealing your personal information, like passwords and credit card numbers, industry experts say.

The purveyors of Trojan Horses can commandeer your computer as an archival tool; making you a host for unlawful activities, such as distributing pornography from your computer, under your name, across the Internet, around the world. Talk about crashing and burning.

Afraid yet?

“Along with pornography hosting, your computer also can be used as a ‘zombie warrior’ in a denial of service attack,” says Tim Rohde, marketing curriculum developer and behavioral analytics consultant for clients including California State University, Fullerton, Remedy Staffing and buy.com.

“In a denial of service Attack,” Rohde says, “a hacker orchestrates the many thousands of computers he’s infected to focus an overwhelming wave of requests on one server or group of servers. This can interfere with legitimate use of those resources and temporarily damage their capacity to resist attempts by hackers to control them.”

While the ramifications of such mass strangleholds of the nation’s computer infrastructure may be frightening to contemplate, especially if focused on financial or health care institutions, public utilities or other fundamental services, we have heard about such threats before. What is far more frightening is the fact that most computer users are unaware of our own involuntary complicity in those threats. In other words, we are unknowingly aiding and abetting the enemy.

“The success of these threats is definitely an indicator of that,” says Oliver Friedrichs, senior manager with Symantec Security Response.

“On any given day, there may be thousands of infected systems that continue to be infected. We’re talking about maybe 60,000 systems, in some cases, at any given time, that are being used to relay spam and also launch further attacks against other systems,” says Friedrichs.

Inviting them in

Often, it is the lure of the aforementioned gifts -- freeware, shareware, those popular chat rooms, that provocative Web site, and even the sacrosanct instant messaging -- that convince us to open the city gates to spies, who use our machines as their own personal stables to breed their galloping steeds of destruction.

The difference between ancient and modern Trojans is that today’s have even more horse sense. They are not out to destroy your system; they are out to use your system to get to other, more interesting systems, which then can be manipulated, exploited or plundered.

“Basically, two years ago the malicious code scene was separated into three parts: viruses, Trojans and worms, in that very particular order,” says Dancho Danchev, a security consultant for Holland-based Frame4 Security Systems and author of numerous white papers on Internet security.

“Worms weren't that popular, and viruses were among the worst nightmares a user could get infected with. Later on, Trojans became more and more popular, and everything shifted from destroying information to controlling information and the victims' computers,” says Danchev.

“Let's put it this way: Viruses have the capability to infect files in the stealthiest way; Trojans have the capacity to gain full and, most importantly, remote control over someone's machine; and spyware, by using Web bugs, has the greatest capacity to infect, hijack and set up the groundwork for infection with the Trojan itself.”

While efforts are clearly being made by Internet security companies to outflank hackers, often the lead is merely by a nose.

“We’re continually trying to evolve our technology to detect threats like this in advance,” says Symantec’s Friedrichs. “That’s really where the industry’s going -- to be able to detect these threats and prevent them before a consumer becomes infected. Like any technology, it really has to evolve and mature before it’s 100 percent there.

“Things are getting better, in terms of defenses, but at the same time, they’re also getting worse, in terms of the capabilities attackers have and how insidious these threats are. We’re seeing a huge network of these individuals who are continually innovating and using this technology,” says Friedrichs. “The level at which they’re doing it is also increasing. The introduction of organized crime and other components has now escalated the entire threat landscape to another level, especially like recent attacks in June, in which they’re specifically targeting financial information on infected systems.”

Tomorrow: Ironically, while I planned this story as an overview of the battle against spyware, I suddenly experienced a “Whoa, Nelly” epiphany. Tune in to learn from my brush with the Horse.

Arthur G. Insana is a freelance writer covering media and technology. He was managing editor of On Location Magazine and is president of CopyWrite Communications, an editorial and entertainment production company, and a best-selling producer/director of audiobooks, audio documentaries and audiodramas, including the full-cast, "Star Wars: Dark Empire" series for Time Warner/Lucasfilm.