Up to 50,128 types of virus appeared in 2009, 1.5 times more than 2008.

The most prevalent virus was SalityVF.PE, which infected 483,000 PCs.

Metamorphic virus like W32.Sality.PE and W32.Vetor.PE topped the list for the most widespread viruses, becoming a challenge for users and anti-virus software.

Metamorphic viruses are dangerous because they can reprogram themselves. This is used by some viruses when they are about to infect new files, and the result is it’s "children" don’t look like their "parents". Computer viruses using this technique do this in order to avoid the pattern recognition of anti-virus software.

According to the Back Khoa Network Security Centre (BKIS), 2.2 million PCs in Vietnam were attacked by this type of virus. They caused serious problems for the system and damaged data.

In addition, a number of fake anti-virus software products appeared, confusing users. By sending emails or using search engines, hackers enticed victims to fake anti-virus websites which have Windows-style interfaces. By visiting these sites, users downloaded fake anti-virus software to their PCs.

In 2009, viruses increased in number and became more complicated.

According to BKIS, this year virus will continue increasing, especially dangerous types like the metamorphic virus. Mobile phones could be the new targets for hackers, especially when the 3G network is available in Vietnam.

The amended Penal Code, which took effect on January 1 2010, will be the foundation for dealing with violations of this kind. In the past, those who spread computer virus were only fined administratively but from now on, this violation may mean imprisonment for up to 12 years.