Worst Computer Viruses Part 1

Mar 27, 2017 | IT Services

In this five-part series (yes, there are so many that this will be five parts), we’ll examine some of the worst computer viruses ever created.

Worst Computer VirusesComputer viruses are a strange thing; it’s not like a regular virus that can spring up from a random mutation in nature. Computer viruses need a creator. Someone has to make a conscious effort to create a program that will cause damage to another person’s computer or network. In this five-part series (yes, there are so many that this will be five parts), we’ll examine some of the worst computer viruses ever created.

The Morris Worm

The first computer worms distributed and the first to gain significant mainstream media attention that infected 2,000 computers in fifteen hours resulting in estimated damages of $100,000-$10,000,000.


Also known as Chernobyl or Spacefiller, is a Microsoft Windows computer virus with a highly destructive payload that overwrites critical information on infected system drives and in some cases destroying the system.

The Anna Kournikova Worm

A computer worm designed to trick email users into opening a message purportedly containing a picture of the tennis player Anna Kournikova while hiding a malicious program. Upon opening the message, the worm rapidly launches a viral Visual Basic Script that forwards itself to everyone in the victim’s Microsoft Outlook address book.


A computer worm that attacked tens of millions of Windows computers via an email message with the subject line “ILOVEYOU” and the attachment “LOVE-LETTER-FOR-YOU.txt.vbs” and opening the attachment activated the basic visual script allowing the worm to damage local machines and overwriting random types of files including Office, image and audio files.

The Melissa Virus

A mass-mailing macro virus distributed via email that when opened allows the virus to be re-sent to the first 50 people in the victim’s Microsoft Outlook contacts with the potential to disable mail servers as the ripple of email distribution becomes a much larger wave.

The Blaster Worm

A computer worm that spreads on computers running Microsoft operating systems. Once a network was infected, it spread quicker within the network because firewalls typically did not prevent internal machines from using a specific port. When infection occurred, the buffer overflow caused the RPC service to crash, leading Windows to display a shutdown message and then automatically reboot usually after 60 seconds.


Sasser is a computer worm that affects computers running vulnerable versions of the Microsoft operating systems, spreading by exploiting the system through a vulnerable port resulting in random crashes.


RSPlug is a malware targeting Mac OSX operating system that when installed the system’s DNS settings were changed to redirect web browsing to phishing websites or web pages displaying ads for adult websites.


A virus that modifies device drivers on an infected system, the modified drivers load Nuwar into memory on system startup, and in some cases, the infection may block system file check from displaying notifications of these system file modifications.

Klez Virus

A worm that infects the victim’s computer through an email message, replicating and sending itself out people in the victim’s address book leading to possible privacy breaches. Variations would use false “From” address, picking an email address at random from the infected machine’s Outlook address book, making it extremely difficult to determine which device is infected.

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