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Virus Information

A virus is a program which reproduces its own code by attaching itself to other programs in such a way that the virus code is executed when the infected program is executed. New computer viruses are found every day.

A virus reproduces, usually without your permission or knowledge. In general terms they have an infection phase where they reproduce widely and an attack phase where they do whatever damage they are programmed to do (if any). There are a large number of virus types.

Make sure you check your system with the latest products in the market. Be aware of free offers from unknown sites. Always check downloaded files with a AntiVirus program. If you think that your computer has a virus, do not panic.

Do not forget to check out the sites mentioned in Virus Prevention. Learn how to prevent getting infected and to secure your system as tight as possible. As a reminder: Viruses do not do any harm, ignorance does.

To receive the latest virus alerts, you could subscribe to a Virus Newsletter distributed by the AV vendor of your choice or to a RSS feed.

Different types of Viruses.

Boot sector virus:
These kind of viruses infects the boot sector of a hard drive or floppy disk. This is done by overwriting or moving the original boot code. After that they try to move the original code to another sector on the disk and mark that sector as bad. Thus leaving you with a hard drive or floppy disk without proper boot sector.

Computer Worms:
See Computer Worms Information.

File infecting virus:
File infecting viruses are the most common ones. They tend to attach or modify all kind of executable files (f.i. 'EXE', '.COM'). It's possible that this virus replaces the original code with its own.

Macro virus:
See Macro Virus Information.

Master Boot Record Infectors:
Infects the system's Master Boot Record on hard drives and the Boot Sector on floppy diskettes.
This type of virus takes control of the system at a low level; activating between the system hardware and the operating system. A Boot Sector virus is loaded into memory upon boot-up, before virus detection code can be executed.

Polymorphic viruses:
Change their appearance with each infectious action. Can be hard to detect 'cause they are using an encryption algorithm that changes everytime. With or after each infection.

Stealth virus:
Yep,.. Stealth virus. These ones try to hide themselves from the operating system and anti-virus products. Doing this by residing in memory and intercepting all operating system access. Even anti-virus products can be fooled this way, thinking that the computer is virus free. Whilst the virus itself intercepts the anti-virus products requests made to the operating system. They even fool you by hiding the fact that it's consuming memory.

Trojan Horse:
See Trojan Horses Information.

Multi-partite virus:
Most common for this type is a combination of techniques of both boot sector viruses and file infecting viruses. Appearance in any combination of the viruses listed above is possible though. F.i. the famous Hare virus (1996) is an polymorphic, stealth, multi-partite virus.

Virus Prevention:

Excellent source of virus prevention tips & tricks. Large database of AV product reviews. Maintained by members of the 'alt.comp.virus' newsgroup.

Huge portal with links from Password Management to Port Scanners, Encryption Applications to Honeypots, Intrusion Detection to Popup Blockers, ...and so on.

Test your AV scanner with this file. Read the page on how it works.

Wide range of info on security tips.

It's all in the name: RUNSAFE !

Around since Nov. 1998 and filled with very practical tips & tricks.

Lot's of useful links. From avoiding Spam to Safe Email and Virus prevention.

Virus prevention advice. Tips on how to fine tune your PC and avoid threats.


Various information:

  • For more information about viruses read the article from Computer Knowledge ,"Free virus tutorial".

  • A very handy tool is Project V-GREP from Virus Bulletin. This is an online and downloadable database. Search through multiple AntiVirus-companies virus descriptions.

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