Computers viruses, worms, ransomware, etc. are kinds of malicious software that no user should take lightly. On several occasions, we have touched upon security steps that each user should take in order to protect its identity and data. Sadly sometimes even when all precautions are taken some malware can still slip through and wreak havoc. Today we are looking at some of the worst or the best, depending on your view that has indeed wreaked plenty of havoc.
10 worst computer viruses in historyIn the list of the 10 most famous computer viruses below, we show the costs, dates, reach, and other key facts. First a note about terms: we use the words “virus” and “worm” interchangeably because most readers search for them that way. But there’s a subtle difference that we explain after the list.
The worst computer virus outbreak in history, Mydoom caused estimated damage of $38 billion in 2004, but its inflation-adjusted cost is actually $52.2 billion. Also known as Novarg, this malware is technically a “worm,” spread by mass emailing. At one point, the Mydoom virus was responsible for 25% of all emails sent.
Mydoom scraped addresses from infected machines, then sent copies of itself to those addresses. It also roped those infected machines into a web of computers called a botnet that performed distributed denial of service (DDoS) attacks. These attacks were intended to shut down a target website or server.
Mydoom is still around today, generating 1% of all phishing emails. That’s no small feat considering the 3.4 billion phishing emails sent each day. By that figure, Mydoom has taken on a life of its own, infecting enough poorly-protected machines to send 1.2 billion copies of itself per year, 16 years after its creation.
Though a $250,000 reward was offered, the developer of this dangerous computer worm was never caught.
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The 2003 Sobig computer virus is actually another worm. It is second only to the Mydoom virus in its scope. The $30 billion figure is a worldwide total, including Canada, the U.K., the U.S., mainland Europe, and Asia. Several versions of the worm were released in quick succession, named Sobig.A through Sobig.F, with Sobig.F being the most damaging.
This cybercriminal program masqueraded as legitimate computer software attached to emails. It disrupted ticketing at Air Canada and interfered with countless other businesses. Despite its widespread damage, the creator of the successful bug was never caught.
Klez is a close third on the list of the worst computer viruses ever created. With nearly $20 billion in estimated damages, it infected about 7.2% of all computers in 2001, or 7 million PCs. The Klez worm sent fake emails, spoofed recognized senders and, among other things, attempted to deactivate other viruses.
As with other viruses and worms, Klez was released in several variants. It infected files, copied itself, and spread throughout each victim’s network. It hung around for years, with each version more destructive than the last.
Windows has come a long way since most of the computer viruses on this list hit the web. Thankfully, built-in protection with Microsoft Defender is always on the watch.
The year 2000’s ILOVEYOU virus worked by sending a bogus “love letter” that looked like a harmless text file. Like Mydoom, this attacker sent copies of itself to every email address in the infected machine’s contact list. Shortly after its May 4 release, it had spread to more than 10 million PCs.
The virus was created by a college student in the Philippines named Onel de Guzman. Lacking funds, he wrote the virus to steal passwords so he could log into online services he wanted to use for free. He reportedly had no idea how far his creation would spread. This virus is also known as Loveletter.
Need to up your remote work security game before there’s another entry on the list of most deadly computer viruses? See our guide: How to Work Remotely and Securely
The 2017 WannaCry computer virus is ransomware, a virus that takes over your computer (or cloud files) and holds them hostage. The WannaCry ransomware ripped through computers in 150 countries, causing massive productivity losses as businesses, hospitals, and government organizations that didn’t pay were forced to rebuild systems from scratch.
The malware raged like wildfire through 200,000 computers worldwide. It stopped when a 22-year-old security researcher in the U.K. found a way to turn it off. Computers with out-of-date operating systems were hit especially hard. That’s why security experts always recommend updating your systems frequently.
In September 2020, one of the potentially largest computer virus attacks in medical history hit Universal Health Services. The U.S. hospital chain, which has more than 400 locations, was reportedly struck by damaging ransomware. The attack forced the cancellation of surgeries and made healthcare workers switch to paper records.
The Zeus computer virus is an online theft tool that hit the web in 2007. A whitepaper by Unisys three years later estimated that it was behind 44% of all banking malware attacks. By then, it had breached 88% of all Fortune 500 companies, 2,500 organizations total, and 76,000 computers in 196 countries.
The Zeus botnet was a group of programs that worked together to take over machines for a remote “bot master.” It originated in Eastern Europe and was used to transfer money to secret bank accounts. More than 100 members of the crime ring behind the virus, mostly in the U.S., were arrested in 2010. It’s not as prominent today, but some of the virus’ source code lives on in newer botnet viruses and worms.
Zeus caused documented damage of $100 million. But the real cost in terms of lost productivity, removal, and undocumented theft is undoubtedly much higher. A $3 billion estimate, adjusted for inflation, puts this virus at a cost of $3.7 billion in today’s dollars.
First observed in 2001, the Code Red computer virus was yet another worm that penetrated 975,000 hosts. It displayed the words “Hacked by Chinese!” across infected web pages, and it ran entirely in each machine’s memory. In most cases it left no trace in hard drives or other storage.
Financial costs are pegged at $2.4 billion. The virus attacked websites of infected computers and delivered a distributed denial of service (DDoS) attack on the U.S. White House’s website, www.whitehouse.gov. In fact, the White House had to change its IP address to defend against Cod Red.
Can your printer get a virus? See our cool infographic: The State of Printer Security
The SQL Slammer worm cost an estimated $750 million across 200,000 computer users in 2003. This computer virus randomly selected IP addresses, exploiting vulnerabilities and sending itself on to other machines. It used these victim machines to launch a DDoS attack on several internet hosts, significantly slowing internet traffic.
The Slammer worm hit banks in the U.S. and Canada especially hard, taking ATMs offline in many locations. Customers of Toronto’s Imperial Bank of Commerce found themselves unable to access funds. The attack reared its ugly head again in 2016, launching from IP addresses in Ukraine, China, and Mexico.
Thankfully, ransomware attacks like the 2013 CryptoLocker virus have dipped since their 2017 peak. This malware attacked upwards of 250,000 machines by encrypting their files. It displayed a red ransom note informing users that “your important files encryption produced on this computer.” A payment window accompanied the note.
The virus’ creators used a worm called the Gameover Zeus botnet to make and send copies of the CryptoLocker virus. According to a report by security firm Sophos, the average ransomware attack costs a business $133,000. If we estimate that CryptoLocker hit 5,000 companies, that would put its total cost at $665 million.
Where will cybersecurity go next? See our guide: The Future of Cybersecurity
The Sasser worm was written by a 17-year-old German computer science student named Sven Jaschan. He was arrested at the age of 18 in 2004 after a $250,000 bounty was posted for the computer virus’ creator. A friend of Jaschan’s tipped authorities that the youth had penned not only the Sasser worm but also the damaging Netsky.AC attack.
Jaschan was given a suspended sentence after it was found he was a minor when he wrote the malware. The Sasser worm crashed millions of PCs, and though some reports put damages at $18 billion, the relatively low infection rate suggests a more likely cost of $500 million.
Other notable viruses
The top 10 worst computer viruses above are just the ugly tip of a gargantuan digital iceberg. With a million new malware programs popping up every 3 years, we may miss the forest for a few outstanding trees. Here are just a few more viruses that have wreaked havoc over the years:
Mimail: This worm tried to harvest data from infected machines to launch a string of DDoS attacks, but was relatively easy to remove.
Yaha: Yet another worm with several variants, thought to be the result of a cyber-war between Pakistan and India.
Swen: Written in C++, the Swen computer worm disguised itself to look like a 2003 OS update. Its financial cost has been pegged at $10.4 billion, but not reliably.
Storm Worm: This worm showed up in 2007 and attacked millions of computers with an email about approaching bad weather.
Tanatos/Bugbear: A 2002 keylogger virus that targeted financial institutions and spread to 150 countries.
Sircam: A computer worm from 2001 that used counterfeit emails with the subject line, “I send you this file in order to have your advice.”
Explorezip: This worm used fake emails to spread to every machine on thousands of local networks.
Melissa: The most dangerous computer virus in 1999, Melissa sent copies of itself that looked like NSFW pics. The U.S. FBI estimated cleanup and repair costs at $80 million.
Flashback: A Mac-only virus, Flashback infected over 600,000 Macs in 2012 and even infected Apple’s home base in Cupertino, Calif. In 2020, there’s now more malware on Macs than on PCs.
Conficker: This 2009 virus still infects many legacy systems and could do significant damage if it ever activates.
Stuxnet: This worm is reported to have destroyed Iranian nuclear centrifuges by sending damaging instructions.

Error CausesAt its most basic level, Error Code 0x8024001b is an error that can cause problems with the installation and updates of software and operating system updates. The most common version of this error appears in Windows 10, but a similar error with a matching code number has been present in previous versions of the operating system, back through Windows 7.
Common symptoms include:
Error CausesThere are two main causes for Error Code 0x8024001b, both of which are fairly simple: Updates needed for the Windows Update tool itself and software that causes Windows Update to fail during installations through conflicts in system files. While these may seem like technical issues, these problems are actually easily resolved with a few simple steps. The average user can use the methods listed below to fix the problems on their own.
For users who want to address Error Code 0x8024001b for themselves, the steps below can be followed to address the two primary causes for the error. If you have difficulty in completing these steps or are not confident in your computing skills and ability to follow the listed steps, contact a Windows repair technician.
Here are the top methods to resolve Error Code 0x8024001b on your own:
In some cases, the Windows Update tool may need an update for itself. When you attempt to run updates or install wizards for other software, it can cause conflicts with the Windows Update process, slowing down your computer or causing it to freeze.
If you are attempting to run multiple installations or updates at the same time, it may also cause Error Code 0x8024001b to arise on your computer.
To resolve this issue, close out all programs, with the exception of the Windows Update tool. Within the tool, select “Check for Updates” and install any updates that are needed. When finished, you should restart your computer to ensure that all updates have been fully applied before attempting any other installations or updates.
Another problem that can cause Error Code 0x8024001b is the presence of conflicting software. If Error Code 0x8024001b has only recently appeared on your computer, consider removing any software that has been added to your computer, running the Windows Update process, and restarting your computer before attempting to reinstall the problem software.
With any method that you use, it is important to remember to keep your Windows Updates current at all times. This is the best way to avoid the appearance of Error Code 0x8024001b and similar errors in the future, as stacked up updates are more likely to cause issues and conflicts with your other installed software and operating system.
While there are some tools out there that claim to be able to fix Error Code 0x8024001b for you, it is important to always thoroughly investigate the publisher and distributor of such software, as some of the tools available on the Internet will actually introduce malware and adware on your computer in the name of “protecting” your computer or resolving an error.
If you have tried to use both methods above and have not fully resolved Error Code 0x8024001b, get in touch with someone who is a qualified computer repair professional and is familiar with your particular version of the Windows operating system to assist you in finalizing your resolution.
If you wish to always have at your disposal a utility tool to fix these Windows 10 and other related issues when they do arise, download and install a powerful automated tool.
Error CausesC:\WINDOWS\system32\usvdgpo.dll.This error message indicates that the program ‘usvdgpo’ is causing the run.dll error on the system. Once the program is identified, the next step is to stop it manually. For this, you go to the start menu and click run, now type ‘services.msc’ in the dialog box, and press ‘Enter’. After that right-click the related process to your rundll error and then click the ‘Stop’ button to stop the program. Now close the window. Though this action will stop the process it will not remove the reference to the bogus items. To remove that you will have to remove the program from the Windows Registry. This can be done by typing ‘Regedit’ in the Run dialog box. This will open the registry editor. From the keys listed in the left panel, navigate to the following key: HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Run. Now right-click on this key and click delete and then simply close the windows registry and reboot your system. After this, you will then have to uninstall the program to completely eradicate the rundll error. To do this, go to the control panel, Add/remove programs, and right-click to uninstall the program causing the run.dll error on your system. Click yes to confirm your decision. Once the program is uninstalled, reinstall the program using the program CD to get yourself an error-free program. This procedure is tricky, time-consuming, and maybe slightly challenging for you especially if you are not a computer programmer.
WeatherGenie is a Browser Extension that allows users to check the current weather in any town at any time. This extension adds the “Weather:” search option to your new tab, and changes your default search engine to Yahoo.com. It also ads system Registry Entities that allow it to run each time the computer is restarted, several task schedulers are also added to allow it to run at various times during the day.
While installing this extension monitor browsing data from your computer. You may also see additional injected ads, sponsored links, and pop-up ads through your browser sessions. Weather games have been marked as a Browser Hijacker by several anti-virus scanners and are therefore not recommended to keep on your computer. It is flagged as potentially unwanted for optional removal.
BigTech platforms Google and Facebook were hit with a series of antitrust lawsuits by the US federal government and states on charges they are operating monopolies and abusing their power.
Below is the status of the cases, as well as government probes of Apple and Amazon in their current states
BringMeSports is a browser extension developed by Mindspark Inc. that lets you watch live sports streams, follow sports scores, and catch up on the latest news from the sports world. BringMeSports installs an extension into your browser that replaces your default home page with the MyWebSearch starting page, it also replaces your default search engine, shows additional ads, and while running, collects personal and web browsing data that is later sent back to be Sold / Forwarded to serve ads. While browsing the internet with this extension installed, you will see additional ads and sponsored links appear in your search results. It may even show pop-up ads. Several anti-virus scanners have marked this extension as a Browser Hijacker and are therefore not recommended to keep on your computer.
chkdsk /f /r
“Not enough USB controller resources. The controller does not have enough resources for this device.”To fix this error, here are some guidelines you can check out. Make sure to follow them carefully.