Almost three quarters of China's computers were attacked by viruses from May 2005 to May 2006, down six percent year-on-year, according to a survey by the Ministry of Public Security.
The annual survey, based on 13,824 questionnaires collected nationwide concerning Internet security problems, showed the vulnerability was mainly due to a lack of maintenance and repair of software.
Internet surfing and downloading to USB flash disks and portable hard disks were major channels for spreading viruses, the survey showed.
More viruses were homegrown, and many intended to profit from illegal activities, the ministry said.
Fifty-four percent of the companies sampled had suffered Internet security problems. Of those companies, 84 percent had computer virus problems, 36 percent suffered from port scanning or Internet attacks, and 35 percent received junk mail.
Officials with the ministry said they would improve advice to companies and promote the training of Internet security personnel to better secure the information network.