Each of Vietnam's seven million computer users suffered an average loss of VND1.25 million (US$55) due to viruses last year, a new report said.
The report, released by Hanoi-based online security firm BKAV, found that up to 83 percent of more than 9.1 million computers in the country were infected with viruses via portable USB devices at least once last year. That was slightly down from 85 percent in 2014.
The most common virus was W32.UsbFakeDrive, according to BKAV, which provides one of the most popular antivirus programs in Vietnam.
It said the total damage was worth VND8.7 trillion ($387 million), up 2.3 percent from the previous year.
BKAV found that 93 percent of Facebook users in Vietnam received spam with pornographic content and links to malware.
Facebook users are now also facing higher risks. Last year, more than 1,000 Facebook pages were created every month to steal other users' data and take over their accounts for fraud.
BKAV said users of social networks need to verify information carefully and not follow instructions of suspicious links.
According to BKAV, more mobile users in Vietnam have been aware of malware and spy apps.
However, there are still 40 percent of mobile device users who do not pay attention to which app they are downloading and from whom.
“Tens of thousands of mobile apps are uploaded every day. It is important to pay attention to the provider and number of downloads to prevent malware infection,” said Vu Ngoc Son, vice president of BKAV.
In 2015, BKAV detected 62,863 new viruses in Vietnam that were responsible for a total of 61.9 million infections.
More than 5,200 websites of government offices and companies in Vietnam were hacked, including 340 websites of central government agencies and educational agencies.