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.
Wondering what makes the world’s most secure computers so safe? See the Tech@Work guide: Upgrade to the World's Most Secure and Manageable PC
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 CausesError Code 46 is a device driver error that occurs when Windows fails to access the connected peripheral device to the computer as Windows is in a process of shutting down.
Users experience this error on any Windows 2000 and later operating system versions and usually see a pop-up with the following message:
“Windows cannot gain access to this hardware device because the operating system is in the process of shutting down. (Code 46)”
Error CausesError Code 46 is caused when there is a temporary problem with windows system files which prompts that the system is undergoing a shut down when in fact is it not.
This prevents access to the connected devices. This error may also be caused by a registry issue in which case it has either become corrupted or damaged.
Unlike all other Windows error codes, code 46 is relatively easy to fix with the right knowledge and does not pose any serious threat to the well-being of your PC. Here is how you can do it.
The simplest method to resolve Error Code 46 is to run a restart of your computer.
The error is most commonly a temporary registry glitch that prevents you from accessing the device connected to your computer. Upon restarting your computer, it will resume working properly as before.
There is no need to run a troubleshooting wizard, use system restore, or run anti-virus software to scan and remove malware or spyware. A simple restart is all that is needed.
Although the error code can be resolved upon restarting the computer, there’s a possibility of damaged or corrupted Windows registry files. This can be fixed by using a program like DriverFIX.
DriverFIX, with its user-friendly approach to help you fix your PC issues, comes with an integrated database that detects which drivers you need to reconfigure within just a few seconds and downloads it automatically.
It further ensures that your drivers are installed in their entirety leaving no room for any corrupted or damaged registry.
Error Code 46 may not be much of an issue, however, to prevent any risk of a Windows system corruption can be disastrous for your computer.
DriverFIX helps you fix your PC registry and device driver problems with user-friendly software and an integrated database. The database which consists of detailed information on what device driver needs to be installed will automatically download the required device driver without you need to refer to your hardware instruction manual.
Registry problems resulting from incomplete program installations and viruses such as malware and spyware damaged registry files. This affects your PC in serious ways.
DriverFIX further has an automatic backup and restoration system that helps create system ‘checkpoints’ which allow you to roll back to a healthier state and resume operations. This can help you avert any Windows error codes in the future.
Click here to download DriverFIX now!
“Error 2738. Could not access VBScript run time for custom action.”It is a type of runtime error associated with VB (Visual Basic) Script. It indicates that the VB script engine is not correctly registered on your computer.
Error CausesThe GifsGalore Toolbar from Mindspark Interactive Network, Inc. is proposed to active Web users who like to embed GIFs into their emails and share entertaining GIFs with friends via social media services. The GifsGalore software can be added to your Internet client for free but you need to be using Google Chrome, Internet Explorer or Mozilla Firefox for the GifsGalore Toolbar to be activated.
When installed it hijacks your New tab page and default search engine changing them to search.myway.com. This extension also monitors user browsing activity recording information such as: visited websites, clicked links, viewed products, etc. This information is later used to better target ads. While browsing the internet with this extension enabled you will see additional pop-up ads, as well as sponsored links and injected ads throughout your browsing session, especially in search results.
DISM.exe /Online /Cleanup-Image /RestoreHealth /Source:C:RepairSourceWindows /LimitAccess
Search Donkey is a Potentially Unwanted Program for Windows developed by Western Web Applications, LLC. This program may inject ads into your browsing sessions, giving you false search results and advertisements.
As described by Western Web Applications: “Search Donkey is entirely free to use. To keep Search Donkey free, we’ve partnered with high-quality ad providers and you may see additional ads when Search Donkey is installed.
While installed, Search Donkey will keep track of your web search queries, allowing it to let you know what pages you already visited, however, this data is also used to better target personal unwanted ads.
Search Donkey has been flagged as a Potentially Unwanted Program (PUP) by several anti-virus scanners, and their website is blacklisted by Google, giving warning to whoever visits it, and due to the nature of this application, it is not recommended to keep on your computer.
Error CausesError code 0xC1900101, 0x20017 in Windows 10 occurs when Windows users attempt to upgrade to Windows 10 but fail to complete the installation process. This Windows error code may occur due to issues with a third-party antivirus program or problems related to a driver or hardware. When this occurs users will receive an error message and their machine will automatically revert to the original operating system on the device. Common symptoms of the error code include the following:
Error CausesTo fix this particular error code affecting Windows 10 devices, you will need to employ at least one manual repair method mentioned within this article. Manual repair methods offer effective solutions as they seek to address the root causes related to Windows error codes. When the manual repair methods are implemented correctly, users are usually able to quickly overcome issues that cause Windows error codes and can thereafter access all the benefits Windows has to offer to its users.
Note, however, that in a few cases where technical skills are required, the need for a Windows repair technician may present itself. In such a case, resort to Windows forums and other resources to access help from a certified Windows professional. Also, consider using an automated tool where necessary.
Some third-party security programs or antivirus software may interfere with the installation process when Windows users attempt to upgrade to Windows 10. To verify if this is the issue causing error code 0xC1900101-0x20017 on your device, temporarily uninstall or disable these applications. You may easily do so by checking the settings of these programs or visiting Settings within the Windows Start Menu.
Once you have disabled these programs on your device, reboot your machine and attempt to update to Windows 10. If the issue was caused by a third-party app, error code 0xC1900101-0x20017 will no longer occur and your machine will successfully upgrade to the version of Windows 10 you attempt to download.
However, in the case where error code 0xC1900101-0x20017 in Windows 10 reoccurs during the installation process, you will need to resort to another manual repair method listed below.
Like method one, this manual repair method can be effective in combating issues related to 0xC1900101-0x20017. This is of course, dependent on whether or not the error code is due to an incompatible security program.
Temporarily disable your firewall by adjusting its settings. Once this step is complete, reboot your machine and attempt to install the latest version of Windows 10. If you are able to complete the process, this means the problem was due to an issue with your firewall. You can then enable the firewall you previously disabled or download another program as its replacement.
If the error code reoccurs, however, consider implementing the next manual repair method on this list.
Command Prompt can be very effective in helping regular as well as technically skilled users repair issues with their PC. In the case of error code 0xC1900101-0x20017 in Windows 10, access Command Prompt using the following instructions.
Be sure to enter the command as it is written above, with a space between “sfc” and “/scannow”. Wait until the scan is complete. If there are any errors related to system files, i.e. if any system files are damaged, corrupted, or missing, your machine will begin to fix it. Once the process is complete, reboot your PC then reattempt the Windows 10 upgrade process via Windows Update. If you are successful, it means that you have rectified error code 0xC1900101-0x20017. Otherwise, you may need to contact a Windows repair technician.
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.
