Computer Viruses

Viruses

In computer technology, viruses are vicious software programs, a form of malware. Viruses exist on local disk drives and spread from one computer to another through the sharing of the infected files. Regular methods for spreading viruses include floppy disks, FTP file transfers, and copying files between shared network drives. Once installed on a computer, a virus may change or remove application and system files. Some viruses can leave a computer inoperable; others just display startling screen messages to innocent users.

Here are five common types of viruses:

Trojan Horse Viruses

A Trojan Horse are computer viruses that hide inside non-executable files such as compressed or document files and executable files and try to avoid detection by anti-virus programs such as Norton or McAfee. Trojan Horses usually appear to be useful computer files / programs such as a computer game or data library.

Polymorphic Viruses

A polymorphic virus is an encrypted virus that hides itself from anti-virus through scrambled data and then decrypts itself to be able to spread through the computer. The thing that makes it hard for anti-virus software to detect polymorphic viruses is that the virus creates and totally new decryption routine each time it infects a new executable file, making the virus signature different in each signature.

Armoured Viruses

An Armoured virus tries to protect itself from anti-virus software by trying to make anti-virus software think it is located somewhere else. Therefore the Armored virus has made itself more difficult to trace, disassemble and understand.

Phage Viruses

A Phage virus is an extremely vicious virus that re-writes an executable program with it's own code, rather than just attaching itself to a file. Therefore a Phage virus will normally try to delete or destroy every program it infects.

Retro Viruses

A Retro virus will attack the anti-virus software planned to delete it. The retro virus generally attempts to attack the anti-virus data files such as the virus signature store, which stops the ability of the anti-virus software