Computer viruses are a major problem for computer users worldwide. They are programs that have the ability to reproduce and infect you system. In addition to being able to reproduce, viruses may be designed to do different destructive actions so a virus can destroy programs and data right away or can stay dormant for some time and do its damage in a certain time therefore Learning about viruses can help you to keep your system free from viruses.
Computer Viruses are becoming more and more sophisticated and are transferred between computer systems using various methods. While email has been the primary method for the spread of these recent computer viruses, it is not the only method. A computer virus can also enter a network by CD, floppy disk, internet download, file sharing programs or by remote users connected to a network with an infected system. Once a computer virus gets into a network it can spread from computer to computer easily.
After viruses infect your system, they may wait for a signal before performing damaging the system: time trigger actions and logic actions. Time actions are signals activated by a specific time or date. Logic actions are activated when specific functions are performed. Most computer viruses show three basic characteristics: a replication process, an activation process, and an objective. The replication mechanism searches for other programs to damage, if it finds any, it inserts the hidden instruction in the program then it modifies the execution sequence of the program. The activation mechanism checks for the occurrence of some event. When the event occurs, the computer virus executes its objective.
Computer viruses have impacted a significant number of computers over the past few years. There are currently over 20,000 known computer viruses worldwide. Over 2000 new viruses are being discovered every month. There are three main types of viruses: Trojan Horses, Worms and Email Viruses.
Trojan Horses- A Trojan named after the Greek army’s tactic of hiding their soldiers in a giant wooden horse that was sent as gift to the city of troy. This virus gets attached to some files in your computer and programs that you download from internet. As a result it starts destroying the file secretly without...