The number of computers infected with viruses from USB flash memory drives is spreading in Japan, according to a survey from Trend Micro.
Results from the company’s monthly surveys show USB-mediated infections with Autorun, a typical computer virus, totaled 143 in August.
The number rose to 347 in September and 471 in October.
Based on the finding, the Tokyo-based virus-scanning software company has called on PC users to take precautions when sharing data with others via USB memory sticks.
Conventional viruses are programmed to attack a computer when a file attached to an e-mail message opens or on-line software is downloaded.
But the September survey found that 53.7 per cent of newly detected computer viruses are programmed to spread via USB devices.
"It is recommended that users refrain from recklessly sharing USB devices. They should frequently run a virus scan," a Trend Micro official said.
USB devices are a "blind spot" for computer users as many of them are only cautious against virus infections via e-mail messages and the Internet.