Is your computer slow? No open programs and you can not get into anything? Well, maybe you have a sick computer. Just as people get sick from the virus, so do computers. When this happens, you must have a technical aspect of computers in the computer to reformat and get rid of the virus. If you know anything about computers, you may be able to do it yourself.

What is a virus?

A virus is a parasitic program written intentionally to enter a computer without the user's permission or knowledge. Parasites word is used because a virus attaches to files or boot sectors and replicates itself, allowing it to spread. Although some viruses are merely copied, others can cause serious damage or affect program and system performance. A virus can not be assumed harmless and left on a system.

Viruses

Viruses are classified by how they infect computer systems:

1) Program: The executable program files such as those ending with the extensions. COM,. EXE,. Ovl. DRV. Sys. Bin
2) Start: Boot Record, Master Boot, FAT and Partition Table.
3) multi: Both program and boot infector.

What is the Trojan Horse?

Besides being a large wooden horse used in the Trojan war 2500 years ago (and more recently by Brad Pitt), a Trojan horse or Trojan is a program that seems innocuous or harmless, but conceals other more unpleasant function. In general, a Trojan is a part of the program brought to your computer from an external source - (download the album for example, diskette, CD, Internet, email and infected). Trojans can be dangerous sometimes. For example, a program may seem like a game demo computer, but at the same time enjoy the game, may be happy to reformat your hard drive or sending an email to all the porn sites in your address book, e-mail.

Trojans are also used as a "backdoor" or a "trap" to slip into the information a computer operating system. An example is a program that aims to be the system log-in program (for example, in Windows NT / XP or Linux). When an unsuspecting user tries to access the system, the Trojan captures the user name and password. You can then indicate a failed logon and access to the real login program. The user can log into the system correctly the next time, but by then Trojan also has enough details to log into the system.

Example Trojans

Notroj. This Trojan pretends to be a program that protects against Trojans. It is actually a time bomb that erases the hard disk after more than 70 percent.

PWSteal.Refest A Trojan horse that installs as a BHO (Browser Helper Object) for Internet Explorer and steals online banking information when presented in web formS.

PWSteal.Likmet. AA Trojan horse that displays a fake MSN Messenger login and password provided steals.

Run.me. This is a graphics program that plays the national anthem and shows the American flag, while the worms its way into the hard drive and erase the data on it.

What is a Worm?

A worm is a self-propagating its way through a system or network (the Internet), often causing damage. Does not require a host program to activate. Someone has to insert a worm directly to the network of interconnected computers where messages can send files to each other and the information and exchange programs. An example is a local area network, where each team has its own files, programs, operating systems and hard drives could be at a university or corporate environment.

Example worms

Worm alarm clock. A worm that spreads through the network to an output terminal (one equipped with a modem), and places to wake up a list of users.

Watcher of the worm. A special program that automatically takes steps to limit the size of a worm, or shut it down, it grows beyond a certain limit. The observer worm also keeps track of changes in the recording operation