Not many software company bosses would have the chutzpah to distribute bright red T-shirts portraying themselves as a latter-day Che Guevara. Not many would take 50 journalists to dinner at a traditional Moscow restaurant and end up doing Cossack dances, or whirling around the ethnically costumed and somewhat embarrassed blonde singer from the balalaika band.

But then, not many founders of Russian software houses have built international businesses and become household names. The casually-dressed, bearded and blue-eyed Evgeniy Valentinovich Kasperskiy, 42, has done all that through the success of his antivirus company, Kaspersky Lab. Which is not to suggest he's some kind of megalomaniac; beer in hand, he's being one of the lads.

He got into the business by accident - he started collecting viruses as a hobby, in 1989, after his PC at the Ministry of Defence became infected with Cascade. By 1991, he'd written an antivirus program to detect and disinfect them, and he co-founded Kaspersky Lab in 1997. The company was named and run for a decade by his ex-wife Natalya after a dispute with a US partner meant they were unable to use their existing product name, AVP. At times, they employed actors to play the Kaspersky figure, but Eugene is too well known for that to work now.

Viral growth

The company that was built on a marriage now has around 800 staff and more than 250 million users worldwide. It's still privately owned, so Kaspersky Lab doesn't have to provide financial results. However, chief financial officer Eugene Buyakin says that 2007 turnover was about $200m (£100m), and if growth continues, it "could be $1bn in five years, maybe less". The aim is to overtake McAfee and become the world's second biggest software security provider.

The virus world has changed as dramatically as the company, and Kaspersky says we're now well into Malware III. The first stage - when he started - was dominated by file infectors and other viruses "developed by kids", which often circulated on floppy disks. The second stage, between 2000 and 2004, was the age of internet worms such as I Love You and Melissa, which often arrived as email attachments.

"Now we live in a world of cybercriminals," says Kaspersky, "the bad guys who develop malware for money - usually they are not ladies! Most infected code is distributed via malicious web pages, and to get people to go there, they use social engineering: spam, phishing emails, blogs, forums, Web 2.0 sites and other social communities."

The Trojans and bots that characterise Malware III are much more sophisticated, and instead of drawing attention to themselves, "they hide, so it's very difficult to find them, and very difficult to remove them. They know how to stay in the system," Kaspersky says. It's a much bigger challenge for security companies than removing known viruses, and suppliers need to add proactive technologies that identify malware behaviour in all types of program.

It's not always easy. Kaspersky remembers one hidden program that, whenever you connected to the net, secretly interacted with an unknown server - "typical spyware". Well, you'd kill that, wouldn't you? It turned out to be an anti-theft system sold to laptop owners, "so then we said sorry," he grins. That's one of the things that fits into what Kaspersky calls the "grey zone", where companies argue about whether things are legitimate or not. It's a problem because malware writers are striving to develop things that don't look like malware. Who decides? He shrugs. "Sometimes we win and sometimes we lose."

The heuristics approach has changed what had been a whack-a-mole market. "In the past, we just followed the bad guys," he says. "They do a trick; we do an anti-trick. Now they're watching us to see if they can find ways round our protection, so it's quite an equal situation now."

Kaspersky also credits Microsoft with starting a trend towards "all-in-one solutions" with its OneCare service, "which also has tune-up and backup. The theory was that it wasn't so much designed to protect customers, but with OneCare, they fixed the three main issues of technical support."

This increases the costs and the range of skills required of companies that want to provide a similar sort of "managed desktop" service. But Kaspersky says "we aren't afraid of Microsoft" (which became one of the Lab's licensees after it bought Sybari in 2005). Security "is one of the most profitable areas, so I'm not surprised they want to get into it," he adds. "But it's priority number 12 for them. Such a big company can't be focused on security, and to do something better than us, they have to focus on it the way we have to focus on it."

Broader horizons

Kaspersky Lab also has to compete with Symantec and McAfee, who sell a lot of subscriptions by being pre-installed on new PCs. Kaspersky says that route has been closed - "Who are you? A small Russian company. But now we're an international company, it's one of the things we plan to do."

And he reckons Kaspersky Lab has advantages in places such as China and Brazil, where the market isn't yet saturated. "For American companies, the American market is always Number One," he says. "For us, it isn't."

In the longer term, Kaspersky Lab is thinking about going public, probably through one of the European stock exchanges. This will make its founders rich. "The main reason is not to get money - we have enough - but to help us to get to the key accounts," he says. "You can't do that easily if you're a private company, especially not the big accounts in the US and the UK."

However, there are no plans to move the company away from Moscow, where the Lab benefits from a healthy supply of graduates who are, like him, well versed in maths, cryptography and programming. He reckons that most of the people who wanted to leave Russia have already left, and some of those are ready to return. Sorry, there's no chance of him moving the business to Oxford, where Kaspersky Lab UK is based.

It could have been different. In the 1990s, Kaspersky thought about taking a job in Aylesbury, working for Dr Alan Solomon, the father of the British anti-virus software industry. However, Natalya couldn't imagine leaving Russia and "considered emigrants to be a kind of traitor". In 1997, Dr Solly sold his S&S International to Network Associates, which turned into McAfee. No doubt a former employee of the Russian defence department will be amused that he could have ended up working for the other side.

· Jack Schofield was a guest on Kaspersky Labs' annual International Press Tour

· This article was amended on Tuesday February 12 2008 because we incorrectly described Eugene Kaspersky as a former lieutenant in the KGB.