Types of Viruses

Computer viruses come in a variety of types. Breaking them into categories is not easy as many viruses have multiple characteristics and so would fall into multiple categories. We’re going to describe two different types of category systems: what they infect and how they infect. Because they are so common, we’re also going to include a category specific to worms.

What They Infect

Viruses can infect a number of different portions of the computer’s operating and file system. These include:

• System Sectors
• Files
• Macros
• Companion Files
• Directories (Cluster) Viruses
• Batch Files
• Source Code
• Visual Basic Files
• Screensavers
• Vulnerabilities

How They Infect

Viruses are sometimes also categorized by how they infect. These categorizations often overlap the categories above and may even be included in the description (e.g., polymorphic file virus). These categories include:

• Polymorphic Viruses
• Stealth Viruses and Rootkits
• Fast and Slow Infectors
• Sparse Infectors
• Armored Viruses
• Multipartite Viruses
• Spacefiller (Cavity) Viruses
• Tunneling Viruses
• Camouflage Viruses
• Metamorphic Viruses
• NTFS ADS Viruses
• Buffer Overflow
• Botnet
• Social Engineering
• Peer-to-Peer Network
• Search Poisoning
• Trusted Software or Site

Blended Threats

And, as you might expect, not all malware operates according to a single rule. Combinations like a Trojan with embedded virus and many other combinations exist. Plus, a single virus may have multiple attack vectors. The categories above are more for understanding a technique than to say these are the single techniques used or even the only techniques used.

Now either click on the virus topic you are interested in or read about each in sequence…

VTutor Home Page
Virus Droppers	What Viruses Infect

Comments from Original Post:

jai
Said this on 2009-06-16 At 11:23 pm
how many type of viruses
#3
DaBoss
Said this on 2009-06-17 At 04:54 pm
In reply to #1
Hard to say exactly as most beasts today are combinations. Above you see 27 different categories. Somebody else might develop a different category set just as valid.
#13
Amitkumar
Said this on 2010-01-06 At 04:13 am
In reply to #1
THERE ARE 8125 TYPES OF VIRUSES [OK. List them! — DaBoss :-)]
#14
pennnie
Said this on 2010-01-19 At 03:23 am
In reply to #1
It is very hard to tell because as time goes on they still produce then and their antiviruses
so I can’t give the number please there are many upcomming
#15
mark
Said this on 2010-03-14 At 03:15 am
In reply to #1
…the types of computer viruses is over 10 million virus that i have been seen,,,

thankx…>>>>>.
#25
U-KISS YUNIKA
Said this on 2010-11-28 At 02:10 am
In reply to #15
How did you know that there’s 10 million virus? 😉
#29
sente
Said this on 2011-07-30 At 10:50 pm
In reply to #15
oh….are you sure?
#16
deepa
Said this on 2010-04-14 At 03:13 am
In reply to #1
how many types of virus
[Read the tutorial. –DaBoss]
#17
deepa
Said this on 2010-04-14 At 03:17 am
In reply to #1
how can we install the the second antivirus in the pc whn other anti virus already instaled
[In general, you should not attempt to install two anti-virus programs on the same PC. They will often interact with each other and protection can be lost. –DaBoss]
#19
R.Shankar
Said this on 2010-06-08 At 09:51 pm
In reply to #1
Till now it cannot be counted crore’s of virus but each day more than 50000 virus are released

#5
abhishek
Said this on 2009-07-08 At 06:48 am
i’m itersted in making a virus .can u teach me how i will make a virus
#6
DaBoss
Said this on 2009-07-08 At 11:17 am
In reply to #5
Let’s see …. No.

#7
mohd shariq asrar
Said this on 2009-07-22 At 10:41 pm
i want to how many type of “VIRUS” ?
AND we read it easily
#8
DaBoss
Said this on 2009-07-22 At 10:44 pm
In reply to #7
See comment #3 above.

#9
amaliena
Said this on 2009-08-19 At 06:13 am
can you put the picture of virus ?
#10
DaBoss
Said this on 2009-08-19 At 12:35 pm
In reply to #9
Picture? No. Some computer viruses do nothing that can be observed; others will have screen displays and the like. But, there is no general picture specific to all viruses.

#11
OLALEKAN
Said this on 2009-11-16 At 11:34 am
Can one avoid virus in his computer even if he does not use antivirus? [Edited by DaBoss to convert the all-caps to non-shouting lower case.]
#12
DaBoss
Said this on 2009-11-16 At 09:41 pm
In reply to #11
You can if you are very careful. It’s a chore however and limits you ability to just explore.

With a Windows machine you’d need to make absolutely certain you keep up with all operating system and program security updates (but with zero-day attacks that’s not a certainty). You’d want to not click on any links in any E-mails, even if you know the sender (malware can easily forge an E-mail header to look genuine). You’d want to run only programs you trust and obtained legally (e.g., NO copied software and only software from known-good vendors). And, limit your time on the Internet to only what’s absolutely necessary. Keep the computer disconnected from the net if not actually using the net.

An easier method would also be to set up a virtual machine and install your known-good operating system and programs into the virtual machine. Then save that system state so you have an always-good, known configuration. Now, do your work in that virtual machine and when done and when you’ve moved any created data files out of the virtual machine to a safe place you can close down the virtual machine and anything and everything on it would disappear. The next day you start over again with a new copy of the original virtual machine. If you do this then you can be a bit more bold in what you do because you know that whatever got onto your computer will be gone when you close the virtual machine. Again, not perfect but not bad as an approach.

Of course, you could also just use a low-infection operating system and do everything on a Linux box. Very few active Linux beasts out there as most malware is directed at Windows machines.

#20
lovely
Said this on 2010-07-14 At 05:31 am
pls. keep me login in to the driverguide.com

[CKnow has no association with them. Please contact them directly for help. –DaBoss]

#21
shahab khan
Said this on 2010-09-26 At 04:51 am
what is the name of anti virus which delete and scan these all types of virus .can some one tell me this anti virus name .i want to install this anti virus which delete and scan all virus.

[Please see this page…

Anti-Virus Software

…for a list of anti-virus software makers. –DaBoss]

Mahesh
Said this on 2010-10-10 At 03:14 pm
How many types of virus & latest which virus attacked in orkut?
#23
DaBoss
Said this on 2010-10-10 At 03:35 pm
In reply to #22
Orkut was attacked the end of September 2010 by the Bom Sabado malware. Appropriate since that means Good Saturday in Portuguese and the virus attacked on a Saturday.

#24
Ranganathan
Said this on 2010-11-09 At 03:27 am
can you briefly explain about the types of viruses.

[It might help to read the article and those following it. –DaBoss]

#26
Sand michal
Said this on 2011-03-12 At 04:39 am
how many types of danger virus & how to create them .
#27
HARRY POM
Said this on 2011-04-14 At 03:54 am
Please many types of viruses, and how does it differ and understand the hardwares and it configuration.

[Please read the tutorial. –DaBoss]

#28
daboss-wannabe
Said this on 2011-06-02 At 06:02 am
Of course, you could also just use a low-infection operating system and do everything on a Linux box. Then save that system state so you have an always-good, known configuration. Now, do your work in that virtual machine and when done and when you’ve moved any created data files out of the virtual machine to a safe place you can close down the virtual machine and anything and everything on it would disappear

[And, of course, you could also use a VM in Windows to do the very same thing. –DaBoss]