China is host to almost half of the world's malware-infected websites.
According to a report released on Monday by antivirus company Sophos, China — including Hong Kong — hosted 44.8 percent of the world's infected sites in August 2007. The US ranked a distant second, hosting 20.8 percent of websites that contain malicious code.
The number of infected web pages has also grown. Sophos said that it detected an average of 5,000 new infected pages each day in the month of August.
The company warned that simply staying clear of sites hosted in the top three countries of China, the US and Russia was not an effective method of avoiding malware.
Carole Theriault, Sophos senior security consultant, said in a statement: "While more than three quarters of infected web pages are hosted in just three countries, that doesn't mean you only get hit if you visit websites based in those areas."
"Hackers are hijacking websites around the world to make them point to malware on sites based in China, the US and Russia. Cybercriminals don't discriminate when it comes to targeting the web," Theriault added.
Sophos also warned against a sharp rise in spam pointing people to these infected sites. Malicious senders, in an attempt to bypass attachment virus scanners, are using messages that direct users to websites with malicious code. Computers get infected when users click on the links in the email message.
"Most malware writers... are using spam and the web to infect users," said Theriault. "Criminals are hard at work trying to slip past filters at the corporate gateway."
June saw a spike in spam hosted on Chinese domains, when the figure rose from almost zero to 450 spam domains.