Rival gangs blamed for PC viruses

It is becoming a daily nightmare for internet users - turn on your PC and you are confronted with a mass of unwanted emails containing viruses.

Until now, there have been few clues to the identity of those responsible for bringing many British businesses to a halt in recent weeks.

But computer experts believe they have got to the bottom of the mystery. They believe there are two rival gangs of virus-writers competing with each other.

Hidden messages have been discovered in the programming code for the viruses, which are crippling email systems around the world.

The two most destructive, Netsky and Bagle, contain messages taunting the rival gang. One version of Netsky even tries to remove the Bagle virus from infected computers.

"It's become a real war of words, and the worrying thing is that there is no end in sight," said Graham Cluley of anti-virus firm Sophos.

"It's a kind of gang warfare, with each writer trying to outdo the other. But these people are giving away clues as they do it, so it may be their downfall in the long run."

Millions of copies of each type of virus have infected computers worldwide. They are also believed to be largely responsible for the huge increase in junk emails.

"They're a spam problem as well as a virus problem now, and people are really feeling the effect every morning when they open their email software," said Mr Cluley.

As the virus infects a machine, it sends itself to every email address it can find, generating thousands of junk emails, all containing the virus. The first hints of the battle were spotted in the Bagle code, which contained the text: "andy; I'm just doing my job, nothing personal".

This was quickly followed by a response from rival Netsky, who released a new version with the text: "Don't ruin our business, you wanna start a war?"

Pete Simpson, of net security firm Clearswift, believes the battle between the virus-writers has turned into a "good versus evil" fight.

He said: "The Netsky authors seem to be basically good: they want to stop Bagle. My feeling is that while the Netsky authors - who we believe come from Russia - are good, the Bagle team is a highly organised crime syndicate. Netsky is a relatively safe virus, it doesn't do anything nasty. Sadly, Bagle is the opposite."

The Bagle virus places an electronic backdoor onto machines it infects, allowing hackers to gain access and effectively hijack the machines. Experts believe these computers are responsible for the majority of junk emails.

"The amazing thing has been the speed of this battle - we've seen four versions in one day, which is a record," said Mr Simpson.

"But the worrying thing is that we don't know when it will stop. The Bagle team are so organised they are obviously professionals, and I would imagine they are making a lot of money by sending junk emails.

"There's really no reason for them to stop, and in the end it is net users who are suffering."