What Is The Most Damaging Virus Attack?

BY Ray Stevens / ON May 04, 2021

This is the story of the computer worm MyDoom, the fastest spreading and most damaging computer virus attack ever.

The idea of a computer virus (a program that can replicate itself very quickly) has existed for over 70 years, and the first article on the subject was written by John von Neumann in 1966.

The first virus ever made, Creeper, is 50 years old this year. Creeper would go on to lay the foundations for one of the most devastating security attacks in recent history, intensifying the need for user awareness of damaging viruses and phishing simulation.

What Is A Computer Worm?

To understand how devastating MyDoom and similar viruses were, we need to know their history and how they work.

A virus is a piece of self-replicating computer code that modifies (or infects) other programs and adds its code, enabling other programs in the system to activate or reactivate the virus’ effects. A computer worm is a standalone computer program that replicates and spreads across a network, taking advantage of weaknesses in security systems to copy itself. The first two worms ever made, Creeper and Reaper, were harmless. Creeper was built to leave a message on networked output machines, while Reaper simply deleted its predecessor.

This type of self-contained virus would become the weapon of choice for some of the most damaging cyberattacks ever.

The Mydoom Attack

It soon became obvious just how quickly a worm could take advantage of an email system and spread a virus. The 1988 Morris Worm, while initially created as an experiment, went on to infect 2,000 computers within a few hours, and the 2000 ILOVEYOU worm ended up on over 10 million Windows devices.

MyDoom was deliberately written as a way to send spam emails to people through infected computers, and went on to become the fastest-spreading worm ever created.

Who Created The MyDoom Virus?

As the author of the virus is unknown, nobody knows for sure the real reason for its creation. Several security firms stated they believed the worm to have originated in Russia, and law enforcement agencies have added they believe organised online criminal gangs to be involved.

What Actually Was The MyDoom Virus?

The virus itself was sent as an email attachment, usually with a subject line replicating an email send error, such as “Mail Transaction Failed” or “Mail Delivery System”. The body of the email says that the unsent message has been included as an attachment.

The executable file looks like a text file, and if clicked, it rapidly installs a system allowing hackers to break into the system, as well as a keylogger to track password input. Next, it scans local files and Outlook’s address books for more email addresses to spread the virus further.

How Much Damage Did MyDoom Cause?

Within a few hours of its first infection on 26th January 2004, the MyDoom virus had slowed the entire internet by 10%, and doubled the amount of time web pages took to load.

The software targeted both Microsoft and a company that had claimed to own the UNIX operating system. This initially caused the belief that the virus was an act of activism created by fans of the open-source system Linux.

Even though this turned out to not to be the case, no virus has done as much damage since MyDoom.

FAQ: What are the most damaging computer viruses?

Aside from MyDoom and the ILOVEYOU virus, which combined caused over $50 million of costs, the Klez worm of 2001 infected almost 10% of all computers, replicating, sending fake emails and attempting to deactivate other viruses.

Two years later the Sobig virus caused $30 billion of damages worldwide, with several versions released (Sobig.F being the most harmful).

FAQ: What are the effects of computer worms?

Worms and their associated viruses have caused astronomical costs; today the figure is estimated at $55 billion a year.

These costs include cleanup and repair, ransomware payments, loss of productivity and fines, however the exact amounts are impossible to tell as issues with cybercrime are not easily tracked.

Luckily, today’s operating systems and advances in security mean that it’s much harder for worms to infiltrate and spread.

FAQ: What are the most recent computer worms?

Most of us have heard of 2017’s WannaCry ransomware, which raged through 200,000 computers and raised over $4 billion. Ransomware went through a peak in the 2010s, such as in the case of the CryptoLocker virus which encrypted files with an accompanying payment window.