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A category with broad experience which keeps out of the new malware dynamic.

What is it?

It is a computer program designed to infect files. In addition, some can have annoying, destructive or even irreparable effects on systems.

When they enter a system, without the user’s consent or knowledge, they are normally hosted within the code of other programs. The virus does not act until the infected program is run. Some of them are programmed to activate when a certain condition is met (a specific date, a certain user action, etc.).

The term ‘virus’ is used due to the similarity with biological viruses. Just as biological viruses enter the human body and infect a cell, which in turn infects new cells, computer viruses enter computers and infect files by inserting their "code". When the infected program is run, the code is activated and the virus begins to spread.

What do they do?

The effects of viruses can be highly annoying to users as an infection of a file can lead to computer slowdowns or alteration of system behavior and functionality.

Viruses normally target executable programs (files with .EXE or .COM extensions). However, they can also infect other types of files, such as web pages (.HTML), Word documents (.DOC), spreadsheets (.XLS), etc.

Viruses can be classified according to several criteria: according to their functionality, the techniques they use to infect, the types of files they infect, the places they hide, the operating system or platforms they attack, etc.

One of the first and most dangerous examples of this category was the virus called Virus Jerusalem.


Viruses have not evolved significantly, as even today they are still created with the same objective: infecting files. Cyber-crooks do not create viruses for financial gain, which is, today, the main objective of these individuals. In fact, these types of threats have been in decline since 2005, as can be seen in the following diagram:

Despite the fact that the objective of viruses has not changed, there has been a change in the way infected files are distributed.

Initially, the spread of a virus was limited to the environment of the infected computer: as most computers were not connected to networks, an infected file would have to be physically transported to a new computer, which was achieved primarily through floppy disks. It would therefore take weeks for a virus to be transmitted, say, from one city to another. However, with the expansion of the Internet, viruses were able to travel around the world in just a few seconds.

Currently, the percentage of malware traffic represented by the Trojans worldwide is: Adware: 20.26%

How can you protect yourself?

Despite the declining prevalence of this type of threat, users should be on their guard and protect themselves against viruses. There are a series of basic measures that users can take to ensure that computers are protected against viruses:

  • Scanning any potentially suspicious files with an antivirus solution.
  • Keeping antivirus programs up-to-date and, if you don’t have an antivirus, you can install any of Panda Security’s antivirus solutions to give you full protection against these and other threats.
  • Running a free antivirus scan of your computer to check whether it is virus-free.

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