Top 10 Computer Viruses
Remember when viruses were just for living things?
By now, computer viruses have become a regular annoyance of modern life and having a sick computer can slow you down far worse than your average cold.
Here are a few computer viruses of note, from the innocent to the malicious.
No. 01 - Storm Virus
Storm gets its name from the trap that is its method of infection.
Starting in early 2007, users began receiving emails with the subject line, "230 dead as storm batters Europe," and a link to the story.
Don't click! No! You've instead been led to an infected site, and you're now downloading the virus, like it or not.
The Storm headlines changed to suit the news, but the virus stayed just as dangerous, infecting as many as a million computers and recruiting them into its botnet.
What's more, Storm has gotten sneakier over time, sending out emails that appear to be from tech support saying to click on a link for a security upgrade (quite the contrary) or sending links to online porn or celebrity photos or even an ecard.
To this day, it remains a major security risk and continues to spread in new ways, including via links inserted into blog postings and bulletin boards. Watch out.
No. 02 - Sasser Virus
The Sasser worm was a destructive beast when it hit in 2004, counting big targets such as the British Coast Guard (which lost its mapping capabilities), Agence France-Presse (which lost its satellite communications) and Delta Airlines (which had to cancel flights when their computer system went down).
Universities, hospitals and large corporations all reported infections that caused computers to repeatedly crash. So, who was responsible for this large-scale act of cyberterror? A rogue cell? An unfriendly government? How about a 17-year-old German kid? Bingo.
Thanks to his young age, Sven Jaschan served no jail time. He was, however, sentenced to 21 months probation and some community service. Ah, youth.
No. 03 - Nimda Virus
Nimda (that's "admin" spelled backward) hit the virus scene in 2001 and quickly (very quickly) rose to the top.
In just 22 minutes, Nimda went from a nothing to being the most widespread computer virus on Earth. How?
It spread via email, via Web sites, via server vulnerabilities. It pretty much had all the bases covered. It even used some old backdoors opened up by past viruses to get into servers and muck up Internet traffic.
As for the fear factor, Nimda had great timing, hitting just a week or so after the Sept. 11 attacks and prompting fear that it was the first in a new wave of Al Qaeda cyberterror attacks.
Those fears turned out to be unfounded and, while a few networks may have crashed, our Internet infrastructure is still standing today.
No. 04 - Melissa Virus
Melissa was a new virus for a new age: the email age. Forget floppies, this one was among the first to spread via the dreaded email attachment.
It also pioneered the art of breaking into your address book and sending itself to all your contacts. The virus would arrive via an innocent-looking email that told you to open a document… and why would you open a document from a stranger? You wouldn't.
Remember the whole address book thing? So, when you got an email from, say, your boss, telling you "Here is that document you asked for," there's a pretty good chance you might open it. Whoops.
Hacker David Smith claimed he wrote the virus for a stripper named Melissa who he had met in Florida. Right, because everyone knows girls are suckers for a destructive bit of code.
No. 05 - Code Red I and II Computer Viruses
The Code Red viruses were very, very sneaky worms.
They didn't require you to do anything to become infected (you didn't need to open an attachment or download a file); all it took was an active Internet connection for the virus to take advantage of a flaw in the Windows operating system. And what did the viruses do?
Well, for one, they turned your computer into a slave, letting someone offsite operate it remotely. That means they could steal what was on your computer or even use your computer to do some bad things…like, say, overloading the White House computers by telling all the infected computers to contact its address.
Luckily, the government was able to shift to another address to escape the attack, but other servers weren't so lucky. In the end, over 200,000 servers were hit by the Code Red virus in 2001.
No. 06 - Morris Computer Virus
The Morris worm started as an experiment, insists Robert Tappan Morris, who in 1988 was a Cornell graduate student.
He distributed the worm in an attempt to gauge how big the then-infant Internet was, but things kind of got out of control from there. The worm spread to some 6,000 university and government computers, slowing them down (and occasionally causing them to crash) as it copied itself (often numerous times on one machine) and spread.
Morris was convicted and fined, but served no time for his little research project. Today, he's a professor at MIT. Let's hope his students have learned from their professor's mistakes.
No. 07 - ILOVEYOU Virus
The ILOVEYOU virus went for the heart, hoping you'd take a chance and open an attachment labeled as a love letter.
Really? People fell for this? Yes.
As many as 10 percent of all Internet-connected computers were infected at the virus's peak in 2000.
The virus spread through the email attachments, but it also replicated itself on a computer's hard drive, directing the computer to download a password-stealing application from the Internet.
Worldwide damage estimates were in the billions of dollars. All for love, right? Yeah, not so much.
No. 08 - Brain Computer Virusr
Brain may not have been the most sophisticated virus, but in 1986 it was the first to really target PCs, via Microsoft's then-dominant DOS operating system.
The virus ate up a huge chunk of memory and caused computers to display a message warning that they had been infected.
It even told them whom they should call to get disinfected: a couple of brothers in Pakistan. Those brothers, the original developers, claim they weren't trying to cause so much trouble; they created the virus as a means of copy protection for their medical software...but then someone else came along and copied that bit of code and the brothers got more than they had bargained for, with pleas for disinfection coming from around the world.
The moral of the story? Be careful what you program.
No. 09 - Conficker
What made Conficker so huge, when it hit in late 2008, was the mystery surrounding it. Ooooh, Conficker.
It had a scary-sounding name and, even scarier, it wasn't really doing anything…yet.
Conficker was assembling an army of computers, called a botnet, but no one was sure where the battle would be.
The virus was telling the infected computers, now potentially zombies, to contact specific sites on certain days...was it to obtain further instructions? Their orders? Who knows?
Most companies and governments installed security patches to protect their computer systems, but some infected machines remain out there, still part of the army.
In theory, they're still ready to serve if Conficker calls.
No. 10 - Elk Cloner
Remember Apple II computers? They were common in school classrooms in the 1980s...which is fitting, because this early virus, perhaps the first to target personal computers, was designed for Apple IIs and written by a high-school kid.
Richard Skrenta was a ninth-grader in 1982 when he wrote the virus, which caused infected computers to display a poem every 50th time they booted up.
That's it, just a poem (ah, we were so innocent back then). Because Elk Cloner was a boot sector virus, it infected any floppy disk that was placed in the computer …which in turn infected other computers.
By now, that kind of stuff is a given, but in 1982, it was groundbreaking.
