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    Top 5 Most Dangerous Computer Viruses

    Dangerous computer viruses

    When we talk about a computer virus, we usually mean any kind of code designed to do harm and spread itself to more computers.

    Viruses are created by malicious programmers who might want to use your computer to attack other targets or make money by stealing your personal information. They could also just be trying to see how far their virus will spread.

    Different viruses can affect Windows, Mac OS, and Linux computers, and even data servers that keep companies, and the internet itself, running. Antivirus program help, but they can have trouble dealing with threats they've never seen before. 

    Over the years, there have been thousands and thousands of viruses spread online, and they've caused billions of dollars of damage from lost productivity, wasted resources, and broken machines. A few dozen of the viruses stand out, some spread especially quickly, or affected a lot of people, or created a ton of damage all by themselves. Some did all of the above. 

    Since a lot of viruses were very bad in a lot of different ways, it's hard to pick out which ones will objectively the worst. But with that in mind here are 5 those extra destructive viruses. These are snippets of code that changed the way people thought about computer security, both the people designing the viruses and people trying to protect them. So let's get started.

    1) Melissa Virus

    Say it's March 1999. You're an unsuspecting computer user who's never gotten a virus, let alone been trained to look for the signs that an email might be malicious. You get an email from someone you know, with a subject line that says it an important message. The message inside just says "Here's that document you asked for don't show it to anyone. 

    The attachment is a Word document labeled "LIST" so you click on it because you're curious and a list of porn sites pops up. At this point, you realize that the email was probably some kind of virus. But it's too late, the first 50 people in your address book have already gotten a copy of the exact same email, with a subject list saying that the message is from you. That was the Melissa Virus.

    The Melissa virus was spread through Microsoft's Outlook email program, and even though the attachment seemed like an innocent word document, it was able to infect the computer because of something called a macro. A macro is a specific kind of computer program that's used to create shortcuts. They're meant to make it easier to edit a document. Instead of making manually a set of changes to the document. Macro is the piece of code that would let you do with 1 click.

    The problem is that functionality gives macros a lot of power over your computer. In just a few days, Melissa spread to hundreds of thousands of computers. It didn't do any damage to computers. But it did make an email service a slow way down and cost companies about $80 million overall.

    The programmer behind this virus was David L.Smith, was caught about a week after Melissa was first released. He spends 20 months in prison and paid a $5000 fine. Why Melissa? Apparently, that was the name of a stripper he met in Florida.


    It was spread on 5 May 2000, was also successful because of social engineering, It reached around 45 million computers in just two days, and caused by $10 billion in damage. The infected mail had the subject line "I LOVE YOU", and came with the attachment title with "love letter for you.txt". 

    When you click on the attachment the virus will go to your system's files looking for media like documents, images, and audio files. Then it would overwrite them with copies of itself, so if you didn't have your file backup, you'd lose all your data. Meanwhile, the virus would send itself to everyone in your address book. It was a type of virus called a worm, which means that it was a standalone program.

    It looked like a text document but that virus file was actually a type of visual basic script which uses the file extension .vbs. Users couldn't see VBS at the end of the filename, though, because the windows OS that they were using was hiding file extension by default. Visual basic script sends your computers a set of instructions to execute. So if they're meant to cause harm it could be very dangerous.

    The Virus was attributed to two programmers in the Philippines. But even though they were both arrested, they were realized at the time, there wasn't any law against what they'd done. 

    3) SQL slammer

    On 25 January 2003 just before 6 a.m, the internet broke. South Korea lost both internet and cell phone service. 300,000 people in Portugal couldn't connect to the internet. Airlines couldn't process tickets and had to cancel flights. Bank ATM's went down. 911 in Seattle had to start using paper to log calls. Even for a lot of devices that were still connected to the internet, the connections had become suddenly very slow, even by 2003 standards.

    Slammer was a worm that targeted SQL servers, which store databases using a piece of Microsoft software called. Microsoft SQL Server. It worked by taking advantage of a bug in the software it sends the server a specially formatted piece of code, one that looked like it was just an ordinary request for information, but actually reprogrammed the server to send out more copies of the same

    The worm spread faster than any other virus ever had, infecting 75,000 servers in just 10 minutes. Those servers were all sending requests to thousands of other servers, which couldn't handle all the traffic. In all millions of servers were affected, and the internet went kaput for a while.

    Slammer is thought to have caused about $1.2 billion in damage before it was stopped, and the programmer behind it was never caught. The whole mess could have been prevented, though six months earlier, Microsoft released a fix for the bug but lots of people just hadn't installed it yet. 

    4) Storm Worm 

    On the 19 January, 2007 Storm worm was another worm that spread through email. But its purpose wasn't to destroy your computer or information, it wanted to take over your computer instead. The original subject line read "230 dead as storm batters Europe", which is where the virus gets its name.

    But instead of an attachment, the email contained a link to a website, which promptly downloaded the virus onto the user's machine. Storm worm was designed to be as invisible as possible so that you wouldn't detect and destroy it. This way it was able to use your computer to do all kinds of stuff in the background.

    The virus would connect your machine to a  botnet a collection of computers that form a network. But at first, the network didn't do actually very much, it just grew up. To make matter worse the anti-virus program had trouble finding a virus on an infected machine. The code form storm worm was designed to change every half hour, so it always looked different. They just sold the network to other criminals and scammers. After a while companies did figure out how to stop the virus from spreading. The people behind it were never caught.


    Mebroot is also a virus that slowly started to spread in 2007. And its main goal was also to hook you up with botnet called torpid. Both are especially sophisticated. It usually gets into your computer via a drive-by download, where you visit a malicious web page and the program starts to download in the background without you even knowing it. From there, it overwrites the master boot record. It is a part of your computer hard drive that stores the instruction that tells your computer how to start up. 

    It can tell your computer what to do right from the start, And what it tells your computer is to connect to the torpid botnet which then steals all of your information. Torpig uses a spying technique known as Man-in-the-browser, which is creepy as it sounds. 

    It lurks in your browser, logging everything you do and any private information you enter. It also tries actively to steal the information, using a fake website that looks and behaves exactly the same as the originals but sends the data to the torpid servers instead. By late 2008 torpid had stolen info connected to 500,000 bank accounts, and again the people who created it haven't been caught.

    How to be safe from viruses?

    There are things you can do to avoid viruses, Install an antivirus program, Don't click on suspicious links or emails. Keep your operating systems and computer programs updated with the latest security patches.

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