The surge came with the rising number of computers contaminated with malware from advanced persistent threats (APT), according to a report released Thursday by Vietnam’s cybersecurity firm BKAV.

The number of computers infected with malware rose 3.5 percent year-on-year to 85.2 million in 2019. This means 57.7 percent of computers nationwide were infected.

Increasing virus infections occurred via email, from 4 percent of the 2018 total to 20 percent last year.

Another reason for the high contamination is Vietnamese users’ habit of downloading files without checking authenticity. Eight out of 10 computers were infected with malware because of this behavior, the report stated.

Rising threats resulted in 1.8 million computers losing data last year, up 12 percent from 2018.

A large-scale foreign attack last year saw the hack of devices via manipulation of weak passwords.

The attack caused 420,000 computers to be infected with the dangerous W32. Fileless malware, which BKAV experts say have "invisibility" as it does not leave behind traces on hardware like other malware.

BKAV forecast malware would become increasingly dangerous this year as hackers use them for financial benefits, like accessing bank accounts.