Virus ABC's

Virus ABCs

One of the biggest fears among new computer users is being infected by a computer virus or programs designed to destroy their personal data. Viruses are malicious software programs that have been designed by other computer users to cause destruction and havoc on a computer and spread themselves to other computers where they can repeat the process.

Once the virus is made, it is often distributed through shareware, pirated software, e-mail, P2P programs, or other programs where users share data.

A computer virus is a program that was first written Rich Skrenta in Computer users can help protect themselves against computer viruses, malware, and other computer security threats by installing an antivirus protection program.
How computer viruses are contracted

In the past the majority of computer viruses were contracted from users sharing data using floppy diskettes. However, with the increased popularity of the Internet most computer viruses are contracted today through e-mail and by downloading software over the Internet or P2P sharing.
How viruses may affect files

Viruses can affect any files; however, usually attack .com, .exe, .sys, .bin, .pif or any data files - Viruses have the capability of infecting any file; however, will generally infect executable files or data files, such as word or excel documents that are opened frequently and allow the virus to try infecting other files more often.

Increase the files size - When infecting files, virtues will generally increase the size of the file; however, with more sophisticated viruses these changes can be hidden.

It can delete files as the file is run - Because most files are loaded into memory, once the program is in memory the virus can delete the file used to execute the virus.

It can corrupt files randomly - Some destructive viruses are not designed to destroy random data but instead randomly delete or corrupt files.

It can cause write protect errors when executing .exe files from a write protected disk - Viruses may need to write themselves to files that are executed; because of this, if a diskette is write protected, you may receive a write protection error.

It can convert .exe files to .com files - Viruses may use a separate file to run the program and rename the original file to another extension so the exe is run before the com.