Dos attacks

Denial-of-service (DoS) attacks, where hackers overload networks with data in an effort to disable them, have risen 50%, a security report says.

The biannual Symantec Threat Report said phishing, where fraudulent e-mails demand passwords from unwitting users, rose 39% in the last six months.

Web security firm Symantec said the trend in cybercrime was towards subtle theft and away from attention-seeking.

It said "crimeware", tailored to steal financial data, was the new threat.

Hackers are using techniques like bot networks, software robots running on unwitting users' machines, to silently commit fraud.

Or the bot-infected computers are used to launch DoS attacks - now running at 1,402 a day - as part of extortion attempts. Phishing attempts are approaching eight million a day.

Targeted methods

Richard Archdeacon, from Symantec, said: "Gone are the days when script-kiddies used to develop attacks which would cause maximum damage and attract as much attention as possible.

"The people behind today's cybercrime are using silent and more targeted methods to steal data and other sensitive information undetected.

"The increased use of bot networks is coupled with the emergence of an online 'mafia' which sees a few 'Mr Bigs' controlling massive parts of the internet for financial gain."

Much of the rise in bot-infected computers was in China, with a 37% growth. The rapid rise in broadband usage is thought to explain some of the trend.

The Symantec researchers said one growth area in the future could be hackers harvesting financial data to sell on to third parties to use in fraud.

The firm advises all users to keep anti-virus software update, install a firewall and install security patches as soon as they are released.