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.
“Connapi.dll Not Found" "This application failed to start because connapi.dll was not found. Re-installing the application may fix this problem." "The file connapi.dll is missing." "Cannot start [APPLICATION]. A required component is missing: connapi.dll. Please install [APPLICATION] again." "Cannot find [PATH]connapi.dll"
Error CausesError Code 0x80060100 is an error that relates to the Windows Update process. It most commonly occurs when the Update process runs and cannot be completed, as the system appears to have necessary files corrupted or absent.
Common symptoms include:
While it can be frustrating when users are not able to complete their necessary updates for Windows 10, there are several solutions that are available to fix the problem at hand. Some of the methods that can be used are simple and accessible, even for beginners, while advanced methods of resolution are also available for users who are more confident in their abilities.
Error Code 0x80060100 appears on Windows 10 and earlier versions of the Windows operating systems. In most cases, the steps to resolve the problem remain the same, regardless of the system on which the error appears. This error code is also related to Error Code 0x800b0100, which appears in similar circumstances.
If the solutions below are not successful in resolving Error Code 0x80060100 on your machine, you may need to get in touch with a qualified repair technician who can assist you in the resolution of the issue at hand. Any repair technician used should be familiar with the needs of the Windows 10 update process.
Error CausesThe primary cause for the appearance of Error Code 0x80060100 on a Windows machine is that the Update files have had damage to them or are found to have elements missing that are necessary for the completion of the Update process.
If Error Code 0x80060100 has appeared on your Windows operating system as you are attempting to download, install, or run Windows Update, there are several steps that you can take to attempt to resolve the error. Some of these methods require advanced knowledge or skills, so if you are not confident in your ability to undertake the steps below, contact a qualified Windows repair technician to assist you in the process.
Here are the best ways to resolve Error Code 0x80060100:
As you attempt to run the Windows Update process and experience difficulty, there is a tool that will usually appear on the screen called the Windows Update Troubleshooter. This process can scan the files being used for the update process and attempt to fix the errors on its own, retrieving or repairing any damaged files as it comes across them.
In most cases, this step on its own will resolve Error Code 0x80060100 on a computer. However, if you are still unable to run Windows Update after using the Troubleshooter, you may need to run a disk repair tool before proceeding.
In some cases, Error Code 0x80060100 can be resolved simply by restarting the computer that is affected by the error. Even if this step is not successful on its own, restarting after each of the other methods can allow necessary changes to take place and refresh the progress of the Windows Update process.
This method requires some skill and knowledge of your operating system. To use this tool, follow the steps below:
If the methods above are not successful in the resolution of Error Code 0x80060100, a qualified Windows repair technician may be able to assist you.
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.
Besides this, you may also experience this error message when you format a hard disk drive to install Windows 7.“An internal error has occurred: The parameter is incorrect: (0x80070057)”
Error CausesError code 12 is a typical Device Manager error code. It usually pops on the computer screen when the computer experiences device driver problems or system resource conflicts.
Error code 12 is mostly displayed on the computer screen in the following format:
‘This device cannot find enough free resources that it can use. If you want to use this device, you will need to disable one of the other devices on this system.’
Error CausesThe error code 12 occurs when 2 devices installed on your PC are accidentally assigned the same I/O (input/output) ports or the same direct memory access channel.
This assignment is known to be made either by BIOS (Basic Input/output system) or by the operating system. It can sometimes be assigned by a combination of the two. Also, code 12 can also appear on your monitor screen if the BIOS didn’t allocate enough resources to the device.
Although this error code is not fatal, it is nonetheless advisable to fix it immediately to avoid inconvenience and hassle. This error is most likely to lower and hamper the performance of your system.
Here are some of the easiest and most effective do-it-yourself methods to resolve error code 12 on your PC. To perform these fixes, you don’t have to be technically sound or a computer programmer for that matter. Simply follow the steps to fix the problem right away.
To repair error code 12, simply go to the start menu and type Device Manager in the search box. Now go to the Device Properties dialog box. After that click on the ‘General Tab’ and now access Troubleshoot to start the Troubleshooting Wizard.
The Wizard will ask you some questions and provide you a solution accordingly. Follow the instructions and resolution steps provided by the troubleshooting wizard to repair error code 12 on your PC.
By disabling the problematic device in the Device Manager, Windows will ignore that piece of hardware. Once disabled, Windows will then no longer assign system resources to that device and no driver/software will be able to use that device.
To disable, go to the Device Properties in the Device Manager and then click the Driver tab. Click disable located at the bottom of the window. Then you will be prompted with a message stating ‘Disabling this device will cause it to stop functioning. Do you wish to disable it?’ Click yes to continue and then click OK to save changes.
Another method to resolve error code 12 is to restore your PC to its previous state when it was working properly.
For this, it is important to backup all your data first to avoid data loss issues that are likely to occur during this process. Creating backups manually can be a time-consuming and tedious task. To save time and quicken the process, it is best to install a program like DriverFIX.
DriverFIX is a user-friendly and intuitive device driver management software that helps backup all your data automatically and efficiently, while simultaneously restores your PC back to its previous state before you encountered problems.
Click here to download DriverFIX on your system to resolve error code 12
Error CausesConvertDocsOnline is a Browser Extension for Google Chrome developed by Mindspark Inc. This extension offers users a quick and easy way to convert documents without any additional applications installed on their computer, it also has quick access links to popular websites that the average user might find interesting. While all this may look appealing and nice, this extension injects itself into your browser.
While installed, ConvertDocsOnline will monitor your browsing activity and record visited websites, clicked links, downloads, and even viewed products. All this information is later used/sold to Mindsparks Ad network to better serve user-targeted ads.
Browsing the internet with this extension installed will result in ad placement throughout your browsing sessions. These ads might appear as normal links (sponsored content), ad links, or even pop-up ads.
ConvertDocsOnline has been marked as a Browser Hijacker by several Anti-Virus scanners and is therefore recommended for optional removal from your PC.
