Computer viruses are not unusual or a new concept. They’ve been troubling the tech-savvy population of the world for many years and will probably do so for many years to come. From jamming an application to rendering a computer inoperable, everything is possible for a computer virus. And just as the sophistication of anti-virus programs is increasing, the complexity and innovation in viruses is also on the rise. There are thousands of people around the world with the spark and craziness to create something which can challenge modern technology at its core. It is such people, rather hackers, who have and continue to give rise to some of the deadliest computer viruses of all time.

We’re not lauding their efforts, but it’s probably because of such hackers that today’s anti-virus programs have gained the niche that they have. Also, the spread of a virus is often the reason that major loopholes in popular applications can be found. And as such, a computer virus which is a threat to security is often the trigger for the invention of better security measures in applications.

So today we’ll take a look at some of the most interesting and worst computer viruses to have hit mankind over the years. But first, a brief description about the forms a virus can take:

Virus: A virus is a computer program which uses a host application to infect a computer. It starts its execution when you run the application which is its host and replicates itself quickly to either eat up your system’s RAM or hard disk space. The host could be anything from an e-mail to a word document or an application setup.

Worm: The end aim and working of a worm is similar to a virus with the difference that it doesn’t need a host application to execute. It can run automatically and also is capable of sending itself across networks.

Trojan: Trojans or Trojan Horses are programs which look to be something but are something else entirely. That is, they claim to do one thing but actually do something else. They can be aimed at either destroying the computer or creating a hole in the computer’s security mechanism such that a remote user or hacker can access the infected system’s data.

Now let’s get the ball rolling.

ILOVEYOU

Probably one of the more popular viruses (a worm and Trojan combo in effect), the ILOVEYOU virus surfaced in May 2000 and travelled as an attachment to an e-mail. The e-mail was depicted to be a love letter from a secret admirer and hence many users couldn’t stop themselves from falling prey to it. It was actually a VB script and was aimed to replicate itself and forward itself to e-mail addresses in the infected e-mailer’s address book. It also included a password stealing program for its creator which auto-downloaded and executed on the machine where the e-mail attachment was opened.

Nimda

The Nimda virus created history in 2001 by becoming the fastest spread Internet virus at that time. It used different Internet means to bring Internet traffic to a halt and infected a record number of machine within 22 minutes of its launch. Its aim was to create a backdoor in the infected machine and allow the creator to access the system with the same permissions that he has. If the victim was a limited access user, the virus creator become so but on the other hand if the victim was an admin, boom!

Sasser & Netsky

Created by the same person, both programs had drastic similarities in the coding but had different modus operandi and aims. Sasser scanned random IP addresses from the infected computer and found its next victims. On the infected system, it made shutting down without removing the power supply nearly impossible. Netsky spread as an e-mail attachment and caused a denial of service attack on infected systems.

Melissa

Named after a dancer from Florida, this virus also spread through e-mail and infected Microsoft Word documents. It inserted a quote from The Simpsons in Word documents and was also capable of replicating itself through self forwarding e-mail. It didn’t manage to bring down the Internet but it sure spread panic in government and private sector networks. E-mails containing this virus became so viral that some organizations had to shut down their e-mail services until the virus was stopped.

Blaster Worm

This worm surfaced in 2003 and attacked systems running on Microsoft Windows operating systems. It spread through specific ports on machines and hence replicated quickly on machines within the same network. This worm is particularly popular for the message displayed on its executable MSBlast.exe. This was a message to Microsoft co-founder Bill Gates asking him to stop making money and start improving Microsoft software security features.

Storm Worm

This virus’s name is attributed to the fact that it was spread through e-mail using the tagline of a news story telling about bad weather condition killing scores of people. All the victims had to do was to click on the link given in the e-mail which was supposed to show the user a news story but in reality downloaded the virus on the computer. Once infecting a computer this virus had the capability to turn it into a zombie. After this, the virus creator could access the infected computers and also use it to send similar spam messages to other computers.

Final Words

These are just some of the many viruses, malware and other harmful programs which crippled the Internet and caused loss of millions of dollars in the past. Viruses will continue to surface in the future too so keep yourself informed, protected and don’t trust suspicious websites or e-mails. Meanwhile, you can use anti-virus software to protect your system from these harmful viruses.

Vikas is an emerging tech blogger who is publishing his first post at PCMEMOIRS. His area of interests are Anti-Virus Software, Apple Software and Gadgets.