Each of Vietnam's seven million computer users suffered an average loss of VND1.23 million ($57.5) due to viruses last year, according to Hanoi-based online security firm BKAV.
The firm, which is behind one of the most popular antivirus softwares in Vietnam, found that up to 85 percent of computers here were infected with viruses via portable USB devices at least once last year.
Even as Microsoft has strengthened protection against viruses in its newer operating systems like Windows 7, many computers in Vietnam are still using older Windows versions, which make them more susceptible to viruses via USB devices, it said.
BKAV's report, released on January 13, includes a wide range of findings from a study that looked into the income of computer users and how long their work was disrupted by virus infections.
The report showed that spam messages nearly doubled from 2013, with 90 percent of computer and mobile phone users frequently receiving spams. More than 40 percent of users were actually spammed every day.
Computer and phone users also faced the threat of harmful codes like Trojans and malware, with relevant damages amounting to a whopping VND3.9 billion a day.
BKAV also warned about security risks that come with using free wifi, especially when 24 percent of users said they accessed free wifi to conduct financial transactions.
The company advised people to use virtual private network (VPN), install antivirus software and turn on firewall for improved security.
It predicted that network security will become a more important issue this year, amid more threats from harmful codes and DDoS attacks.