Much like their biological counterparts, computer viruses wreak havoc once they enter the host; in this case, a computer. Viruses are self-replicating pieces of code that attach onto your files and applications, and cause your computer to do things you don’t want it to do. With symptoms similar to a ‘common cold’ in humans, viruses spread rapidly through networks, causing billions of dollars worth of damage in a short span of time.

Here’s how viruses work:

A file virus attaches itself to a file, usually an executable application, such as a word processing programme or a spreadsheet application. In general, file viruses do not infect data files. However, data files are liable to contain executable codes, such as macros, which may be used by viruses or Trojan Horses. Text files, such as batch files and postscript files, contain commands that can be compiled or interpreted by another programme are potential targets for malware.

Boot sector viruses alter the programme that is in the first sector of every DOS-formatted disk. Generally, a boot sector virus executes its own code, and then affects the PC start-up process.

Multipartite viruses have some of the features of both the above-mentioned types of viruses. Typically, when an infected file is executed, it infects the hard disk boot sector or partition sector and thus infects subsequent disks used on the target system.

Macro viruses typically infect files such as Word templates so that subsequently edited documents are contaminated with the infected macros.

Polymorphic viruses change code whenever they pass through another machine.

Stealth viruses work by making the user believe that the infected file is not infected.

Viruses work in a variety of ways to disrupt your computer, but the most common method is to simply overburden your machine by repeating the same messages over and over via rapid self-replications, eventually crashing the system. In addition, a computer virus may not take effect immediately. It can sit undetected in computer systems for months waiting for the right operation to trigger it into action. By that time, it may be too late!

Stay tuned to the next article where you will learn the symptoms or signs that your computer has been infected by a virus!