The US has once again topped a list of spam producing countries. One in three (35.7 per cent) of the spam messages intercepted by security firm Sophos's global network of spam traps between January and March 2005 came from the USA. South Korea, second in the chart, accounted for a further 25 per cent of junk messages, with third place China accounting for 9.7 per cent of spam email trapped by Sophos.
"Although the USA is responsible for producing more than a third of all of the world's spam, its percentage contribution has decreased," said Graham Cluley, senior technology consultant for Sophos. "The percentage of spam sent from American computers has fallen 12 per cent since the start of the year compared to other countries. ISPs [are] enforcing policies to ensure they do not knowingly provide network services to spammers."
Sophos reckons 60 per cent of the world's spam comes from compromised, zombie computers. This popular spammer tactic means home PCs are often commandeered by hackers and used to send junk mail without their owner's knowledge. Security firms and government agencies have joined forces over recent months to urge users to take basic security precautions (such as keeping Windows boxes up to date with patches and running anti-virus software with the latest signature updates) in order to combat the problem.
Sophos researchers say that an unprotected Windows XP computer (without any firewall, patches or anti-virus protection) stands a 50 per cent chance of infection by an internet worm after just nine minutes plugged onto the net. After 40 minutes there is a 90 per cent chance of infection. source