Everyone dreads being the recipient of a computer virus, but not everyone minds studying them. There are researchers who spend a lot of time looking into different types of computer viruses and related security threats in order to determine how they’re programmed, how they do damage, and how they spread. Personally, I find this field interesting, and I enjoy reading about the different types of viruses in existence.
But even if you don’t know much care, basic knowledge about security threats can be useful. It’s sometimes hard to know how a risk must be dealt with before you know its consequences. With a computer virus, however, the consequence is sometimes complete loss of your data or identity theft – so it’s best to learn sooner rather than later!
1. Boot Sector Virus
hijacks certain browser functions, usually in the form of re-directing the user automatically to particular sites. It’s usually assumed that this tactic is designed to increase revenue from web advertisements.
There are a lot of such viruses, and they usually have “search” included somewhere in their description. CoolWebSearch may be the most well known example, but others are nearly as common.
3. Direct Action Virus
This type of virus, unlike most, only comes into action when the file containing the virus is executed. The payload is delivered and then the virus essentially becomes dormant – it takes no other action unless an infected file is executed again.
Most viruses do not use the direct action method of reproduction simply because it is not prolific, but viruses of this type have done damage in the past. The Vienna virus, which briefly threatened computers in 1988, is one such example of a direct action virus.
4. File Infector Virus
Melissa, a Word document supposedly containing the passwords to pornographic websites. The virus also exploited Word’s link to Microsoft Outlook in order to automatically email copies of itself.
6. Multipartite Virus
While some viruses are happy to spread via one method or deliver a single payload, Multipartite viruses want it all. A virus of this type may spread in multiple ways, and it may take different actions on an infected computer depending on variables, such as the operating system installed or the existence of certain files.
7. Polymorphic Virus
online video in your browser, for example, requires the execution of a specific code language that provides both the video itself and the player interface.
Of course, this code can sometimes be exploited, making it possible for a virus to infect a computer or take actions on a computer through a website. Although malicious sites are sometimes created with purposely infected code, many such cases of virus exist because of code inserted into a site without the webmaster’s knowledge.
I’ve included every type of computer virus in this article that I felt was relevant, but this isn’t a list of every type of virus known to man. Also, I did not include any worms or trojans, two common threats that are similar to viruses but technically not the same. If there is a specific type of virus that you feel was missed and is important, let us know in the comments.
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