Number of Viruses

There were over 50,000 computer viruses in 2000 and that number was then and still is growing rapidly. Sophos, in a print ad in June 2005 claims “over 103,000 viruses.” And, Symantec, in April 2008 is reported to have claimed the number is over one million. Fortunately, only a small percentage of these are circulating widely.

There are more MS-DOS/Windows viruses than all other types of viruses combined (by a large margin). Estimates of exactly how many there are vary widely and the number is constantly growing.

In 1990, estimates ranged from 200 to 500; then in 1991 estimates ranged from 600 to 1,000 different viruses. In late 1992, estimates were ranging from 1,000 to 2,300 viruses. In mid-1994, the numbers vary from 4,500 to over 7,500 viruses. In 1996 the number climbed over 10,000. 1998 saw 20,000 and 2000 topped 50,000. It’s easy to say there are more now. Indeed, in April 2008, the BBC reportedWeb Link that Symantec now claims “that the security firm’s anti-virus programs detect to 1,122,311” viruses and that “almost two thirds of all malicious code threats currently detected were created during 2007.”

The confusion exists partly because it’s difficult to agree on how to count viruses. New viruses frequently arise from someone taking an existing virus that does something like put a message out on your screen saying: “Your PC is now stoned” and changing it to say something like “Donald Duck is a lie!”. Is this a new virus? Most experts say yes. But, this is a trivial change that can be done in less than two minutes resulting in yet another “new” virus.

More confusion arises with some companies counting viruses+worms+Trojans as a unit and some not.

Another problem comes from viruses that try to conceal themselves from scanners by mutating. In other words, every time the virus infects another file, it will try to use a different version of itself. These viruses are known as polymorphic viruses.

One example, the Whale (an early, huge, clumsy 10,000 byte virus), creates 33 different versions of itself when it infects files. At least one vendor counted this as 33 different viruses on their list. Many of the large number of viruses known to exist have not been detected in the wild but probably exist only in someone’s virus collection.

David M. Chess of IBM’s High Integrity Computing Laboratory reported in the November 1991 Virus Bulletin that “about 30 different viruses and variants account for nearly all of the actual infections that we see in day-to-day operation.” In late 2007, about 580 different viruses, worms, and Trojans (and some of these are members of a single family) account for all the virus-related malware that actually spread in the wild. To keep track visit the WildlistWeb Link, a list which reports virus sightings.

How can there be so few viruses active when some experts report such high numbers? This is probably because most viruses are poorly written and cannot spread at all or cannot spread without betraying their presence. Although the actual number of viruses will probably continue to be hotly debated, what is clear is that the total number of viruses is increasing, although the active viruses not quite as rapidly as the numbers might suggest.


  • By number, there are well over 100,000 known computer viruses.
  • Only a small percentage of this total number account for those viruses found in the wild, however. Most exist only in collections.
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Virus Behavior Virus Names

Comments from Original Post:

Said this on 2009-07-06 At 03:37 am
I want to know a lots about virus as virus names, proccess of virus, and how to stop proccess of virus and kill virus?
thank you !
Said this on 2009-07-06 At 11:08 am
In reply to #1
Then, you should start following the anti-virus sites and take some classes. A good starting place is here:

And, then also search through their analysis of various viruses and learn from that.

Good luck.

Said this on 2009-10-09 At 03:44 pm
I’ve been recently researching security and good ways to protect your computer from all kinds of viruses. First are some great, safe security programs that not only protect your computer, but also allow you to run some other programs like a Free Space cleaner and such: – IObit Security 360:
Update: Yes
Version: Free or Full (Purchase required)
Scan(s): Full, Quick, Smart
Hard Drive Space: 20.28 MB
Tray Disk Space: 20.30 MB (Disableable) (the tray disk space thing is the automatic shield similar to McAfee’s that runs a constant shield on your computer. Although it is helpful it is not a necessity and you can disable it if it slows your computer down too much by right-clicking the icon at the bottom right of your screen and selecting “exit.”)
Other Tools: Free Space Cleaner, Privacy Sweeper, Hijack Scan
Typical Scan Run-time: 0 hours, 20 minutes – Malwarebytes’ Anti-Malware
Update: Yes
Versions: Free and Expert (payment required)
Scans: Full, Quick
Hard Drive Space: 32.49 MB
Tray Disk Space: 0 KB
Typical Scan Run-time: 1 hours, 45 minutes

They are both free, another program that requires subscription and payment is Norton Internet Security. If you run back-to-back scans with these programs everyday and keep them updated your computer will remain safe and secure.

Thank you CKnow for these awesome tutorials! They helped better my understanding of viruses.

hemanth roy
Said this on 2010-04-16 At 05:04 am
send me latest s/w updates
[Please contact your anti-virus vendor. –DaBoss]

Said this on 2010-05-04 At 08:43 am
Just try a Mac and be done with all this virus stuff.
Said this on 2010-05-04 At 11:45 am
In reply to #6
Ahhhh, another person who knows not of what they speak. You might want to check out the facts about Macs and viruses…

…as it took the Black Hat people about 20 seconds or so to break into the operating system the last time there was a contest.
Ronald T. Belanger
Said this on 2010-05-22 At 09:41 am
In reply to #7
How many viruses on the Mac vs. how many viruses on the PC?
Said this on 2010-05-22 At 09:45 am
In reply to #10
I can’t give you specific numbers but there are far fewer for a variety of reasons; mostly attributed to the market being so much smaller overall. Virus writers in the past were motivated by how far their virus can spread. Today, it’s more how much money can it generate. With the Windows installed base that still makes Windows the larger target.
Ronald T. Belanger
Said this on 2010-05-26 At 02:56 pm
In reply to #11
Well, I’ll give you the answer::
Mac before OS X: 60 – 80 viruses.
Mac after OS X: 0 viruses.
PC: more than 10,000 viruses.
Said this on 2010-05-26 At 07:54 pm
In reply to #12
And, you would be wrong…

Ronald T. Belanger
Said this on 2010-06-20 At 01:25 pm
In reply to #13
“And, you would be wrong”
O.K. you know the truth. Then what are the real numbers?
Said this on 2010-06-20 At 07:40 pm
In reply to #14
Sighhhhh. Please read the article. Numbers are not important and vary depending who you ask and how they counted the many variants of malware out there.

I said you were wrong about OSX having zero and pointed you to the first one found for that OS. There have been more and Apple even admits that because it has a scanner of sorts built into the OS and updates the list of things looked for on a semi-regular basis.

Apple has fewer viruses than Windows. OK, satisfied now? But, it still has some.

How many exactly? Ask your friendly local anti-virus software company as I don’t keep an exact count.

Said this on 2010-05-10 At 12:08 am
I would like to ask that is there any procedure to clean the virus from the system without using any antivirus.
Said this on 2010-05-10 At 12:15 am
In reply to #8
There is no single way to remove all viruses from a system. Each changes different things and installs in different ways. You could read the way the virus works on various anti-virus websites and then reverse those steps but that’s not always possible as you might have a variant that changes a different file not in the writeup. Of course you could always just reformat the disk and reinstall Windows and all programs and data from scratch or backups made before the virus attack. That, at least, would guarantee a clean system. An image backup would also serve the purpose you ask about. Make frequent image backups and then if you attacked you can restore the disk to the pre-attack state. But, most people don’t have the patience to do this regularly.

Said this on 2010-10-30 At 01:46 pm
Does anyone know what are total number of viruses [by good guys] detected so far? [I am looking for latest number-2010]

[I’d have to say zero because “good guys” don’t write viruses. But, let’s see what happens. –DaBoss]

Said this on 2011-01-06 At 08:58 am

I would like to ask. Is there any open problems in computer viruses? Most websites state that there is no way to research in this area? Are they right?


[There are many open computer virus and malware issues. Just follow the blogs at any of the anti-virus makers’ sites and you’ll see what the current issues are. –DaBoss]

Philip Day
Said this on 2011-02-17 At 09:05 pm
There are no Mac viruses that spread over the internet.
There are about 6-10 pieces of Mac-specific malware/trojan ( if you don’t know the difference between a virus and malware/trojans, you shouldn’t be offering an opinion here).
That said, social engineering attacks don’t depend on the platform, so ALL should be vigilant to this form of attack..
If someone (cough: all of the ant-virii companies and Windows pundits) aren’t willing to cough up the actual number of viruses, their names and description, then you can safely assume they are selling snake oil. Macs and other Unix based platforms are safer in the real world

[There are few actual viruses spreading anywhere today. Mostly Trojans and other malware regardless of platform. Some OSX malware descriptions can be found here: (not a complete list any any means). Social engineering is rampant and does affect every platform. One can be safer but not safe depending on many factors and how much risk they want to take. A person who is running the very latest version of the best anti-virus/anti-malware software can still become infected if they do stupid things. Operating system is only one factor in the equation. -DaBoss]

Said this on 2011-03-11 At 12:34 am
please mail in computer basics sir

[Sorry, you’ll have to learn on your own. –DaBoss]