The Top 3 Most Dangerous Computer Viruses

The Top 3 Most Dangerous Computer Viruses

Computer viruses have come a long way since the very first one in early 1970s. Back in those days, computer viruses were basically self-replicating programs which didn’t do a lot of harmful activities (or anything harmful at all).

Most were intended as academic testing purposes, and some were pretty much intended as jokes. The first virus in the wild was Elk Cloner, which essentially cloned itself from floppy disks to spread and upon 50th use, it will show a poem.

Since then, viruses were developed with different purposes. These days when you talk about a computer virus, you think about malicious programs with evil intentions.

For good reasons, too.

Do you know how much destruction computer viruses are causing every year?


Yes, that’s in dollars. Millions of computers get infected every year, and billions of dollars are lost.

The Top 3 Most Dangerous Computer Viruses

Eh… Why?

Sure, computer viruses only infect the software and don’t destroy the hardware. So for most uninitiated people or those who luckily have never been infected by a virus, they probably will have a hard time to understand why a virus can cost so much damage.

All computer viruses can only infect and destroy software on the computer, or in some cases like CIH virus, it infects the controller firmware on a chipset.

When a virus infects the computers of an organization, what usually happens is that their work will be more or less disrupted. It can be difficult to work on a computer that is infected by a virus.

So, this usually translates into losing working hours. Then if the infecting virus is particularly destructive and destroys certain file formats, there is a chance of losing your work data too.

Then there is the virus removal. It is not really easy to remove a virus if it is a new one. Even if it is an old virus, which is already detected by an antivirus company, you may have to buy new antivirus software just to remove it, if your current software cannot remove the virus. And that comes at a price.

Assuming it is a new virus and you need a professional virus removal service that also doesn’t come cheap. Usually those services are billable by hour and it can cost quite a lot.

Hardware Destroying Virus

Although the days of viruses only infecting and destroying software are far from over, it seems like newer viruses that can destroy and affect hardware are coming out, too.

We will touch more on that later, but for now, those viruses seem to be used for espionage warfare so most personal computer users are still safe from them. However, chances are high that such viruses might be used to affect and destroy computers of certain organizations so we will be seeing those kinds of viruses targeting commercial companies in the future.

And the Most Dangerous Virus Is?

Unfortunate news for all of us is that there is not just one most dangerous virus but a lot.

It is a fact, actually. A lot of viruses in the wild are really dangerous and can cause serious damages. On top of that, new viruses are coming out literally everyday, too.

There are a lot of variations and different versions of current viruses that are already in existence. Hackers behind those viruses are continually releasing updated versions to fix the loopholes in previous versions and avoid detection by antivirus companies.

These days, even a simple virus can be quite complicated and do more than just one harmful and malicious activity. And the real complex viruses? It can hurt our brains even to think about what they are capable of doing to a computer system.

But our team at does exactly that. We test and analyze viruses and antivirus products. We know and understand how important it is for organizations and individual users to protect their computers from viruses.

Among countless numbers of viruses we have encountered, there are a few that standout. We won’t be able to talk about all of them here. It’s simply not possible.

However, here are the top 3 viruses that we have tested and want to talk about. They are considered the most dangerous viruses of all in existence. While some of them may not target normal users at the moment, they demonstrate what viruses can do, if the right people take the time to create them.

So let’s start.

1. Stuxnet

If you have ever watched movies with plots about hackers, cyber warfare, NSA, and viruses, almost always we will see things like destroying a physical target using viruses. It can be anything from oil-carrying ships to missile defense systems. But we always thought that such thing only existed in movies.

That’s until Stuxnet came along. It was like the villain from comics coming to life. Stuxnet was the very first computer virus designed specially to cause damage in the real world, not the virtual world. Like we said, previous viruses before Stuxnet only caused physical problems indirectly by causing problems in the virtual world first. But Stuxnet? It was designed to target software which controls industrial systems, which can then damage all the machinery controlled by those systems.

It was created to damage Iran’s uranium enrichment facility in Nantanz, and data from the International Atomic Energy Agency revealed that Stuxnet caused a large number of Iran’s centrifuges to go nuts and self-destruct. Centrifuges are basically gigantic washing machines used to enrich uranium.

The virus was discovered in 2010, but experts believed that it had infected computers in Iran since 2009.

Stuxnet is very complex and has perhaps the most complicated codebase to date. Experts believe that only nation-states can produce such a massively complex codebase as it requires extensive knowledge in industrial processes, intelligent programmers and hackers. Many speculate that the US government and Israel worked together to create Stuxnet.

Regardless of how true those speculations are, you are probably safe from being infected by a virus like Stuxnet. For something that costs so much money and man-hours, no individual hackers or group of hackers will develop something as complex and dangerous as Stuxnet just to mess around with the general public.

But then for big corporations, they might have reasons to fear a similar virus from infecting them since it is very possible to use such viruses in corporate cyber warfare.

2. Conficker Virus

Conficker is basically a worm which used security loopholes and weaknesses in Microsoft Windows to crawl its way into millions of Windows computers around the world.

Unlike other viruses, it doesn’t do anything harmful on its own. Instead, it essentially created a massive botnet army of remotely controlled computers. These botnets can steal financial data and a lot of other personal information.

But strangely, even though the Conficker worm had infected millions of computers, no one really knows what it was meant to do. The reason? The botnet army was never activated to be used for any specific purpose.

It is really a complex worm and very difficult to stop. Heck, Conficker even prompted the creation of a coalition of experts to stop its spread. Unfortunately, Conficker still somehow infects a large number of computers, even though patches for Microsoft Windows have been released.

The Conficker virus has a few versions, actually. The creators updated the virus to make it more difficult to detect and also patched its own weaknesses. The self-defense mechanisms of the Conficker virus is astoundingly good.

The virus infected not just commercial entities’ and individual computers, but also computers of various governmental organizations such as the French Navy, the UK Ministry of Defence, the unified armed forces of Germany and a whole lot more.

Thank god the botnet army itself was never activated! We guess it will still remain a mystery to all of us. The author of the Conficker virus has never been determined.

3. Agent.btz

When a virus singlehandedly started a new military department under the United States government, it deserves a place in this list. Agent.btz did exactly that. In fact, it infected the entire Pentagon and they even had to issue a ban on flash drives. The U.S. Cyber Command department was created because of Agent.btz.<

Military IT experts found the virus on Pentagon computers in 2008 and they suspected it was the work of foreign spies. Former Deputy Secretary of Defense William Lynne even wrote that agent.btz was capable of creating a digital beachhead, which can transfer data to servers under foreign control.

The worm was pretty sophisticated and it took the Pentagon 14 months to clean it entirely from their systems. That’s a pretty long time for an organization like the Pentagon, and it shows how capable Agent.btz was at infecting the computers.

Although now that the worm is obsolete and no new variations have been found, an official from the Department of Homeland Security said in an article in 2011 that the worm is still evolving and infecting computers.

4 Responses to “The Top 3 Most Dangerous Computer Viruses”

  1. In my experience, I never had any issue of these type of viruses which you mentioned over here but I think I have to keep this post for future. I hope it will help me if something come to me.


  2. Suraj Kumar says:

    The things you have told are knowledge providing. I was not aware of such a dangerous viruses that you have told. Thanks for sharing this kind of amazing knowledge. Keep it up :).

  3. vivek says:

    Nice article.Its great there are many virus but this major is most powerful.

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