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.
A stop error or exception error commonly called the blue screen of death (BSoD) or blue screen, is an error screen displayed on Windows computers following a fatal system error. It indicates a system crash, in which the operating system has reached a condition where it can no longer operate safely. This is caused by many different problems, such as a general hardware failure or a crucial process terminating unexpectedly.
On Windows 10 systems, a Black Screen of Death can be caused by an unfinished Windows Update. To resolve this problem, simply hold the power button down on your PC or laptop to switch off the computer. A cold start should result in the system booting properly.
It is a diagnostic screen with a white type on a pink background. Pink Screen is mainly seen when the VMkernel of an ESX/ESXi host experiences a critical error, becomes inoperative, and terminates any virtual machines that are running. It is not fatal and generally considered more of a developer testing issue. When encountered, it can be fixed quickly by following the simple action of pressing and holding your computer’s power button to shut down the device.
The Microsoft Windows 10 Operating System Brown Screen of Death is an on-screen fatal error notification with bug check codes which is seen when a computer crashes due to graphics hardware or software-related problems (failing graphics drivers).
It affects the functioning of a browser, particularly Mozilla Firefox. The Yellow Screen of Death makes the appearance with a weird buzzing sound in the background when the XML parser refuses to process an XML document causing a parsing error and a weird buzzing sound. The issue persists unless the computer is manually rebooted.
Commonly the Windows 10 red screen is caused due to the hardware error, particularly if you overclock your Windows PC/laptop. Despite this, sometimes the red screen of death is also caused by outdated or incompatible drivers or due to BIOS issues.
The Orange Screen of Death on Windows occurs due to fatal hardware errors. Multiple reasons have been reported for the Orange Screen of Death. Some had this issue when watching a YouTube video, some were not able to boot into Windows. It can even occur when waking up from Sleep.
The green screen of death only appears when you're running an Insider Preview version of Windows 10. It's the same as the blue screen of death, and it will show the same error messages. ... If you see a green screen of death (GSOD) on your PC, that's a sign you're using an Insider Preview build of Windows 10.
The White Screen on Windows is also an error where the screen of the computer just turns white and freezes. There can be several things that can cause the white screen to appear on the Windows laptop monitor. But the main issue could be because of malfunctioning of the graphics hardware. 
GuideError code 0xd0000272 is an activation error code that occurs when Windows users are unable to activate their Windows operating system. This error code features common symptoms which include the following:
Error CausesWhen error code 0xd0000272 occurs in Windows 10, it is usually due to issues related to the Windows activation servers. In such a case where the error code occurs due to an activation server that is temporarily unavailable, users may need to wait for a few hours until the activation server is available. Their copy of Windows will then be automatically activated. Once the activation process is not done accordingly, you might encounter other Windows 10 errors such as error code 0xc004f034.
As is the case with many activation error codes, Windows 10 users can perform several manual repair methods to determine the cause as well as fix the error code affecting their device. Instead of passively waiting to see if your activation error code will be fixed on its own, resolve error code 0xd0000272 through the manual repair methods available. Below are simple instructions that when followed can lead to your success.
Check Settings to verify if your machine is connected to the Internet. This is one of the causes of various error codes which affect Windows 10. Also, this manual method is a simple process that can help Windows users recognize or eliminate factors that may or may not be affecting their system. To check your Internet connection, follow the simple instructions below.
Once you’ve been able to verify an Internet connection or troubleshoot any issues related to your network, go to Update & security. Make an attempt to activate your system. If you are successful, you will be able to access all the features and benefits offered via your copy of Windows. However, move to the next manual method below if error code 0xd0000272 reoccurs.
Your inability to activate Windows 10 may be related to an issue with Windows Update. To verify whether or not Windows Update is functioning properly, run Windows Update Troubleshooter.
You’ll need to visit the Microsoft website to access their Windows Update Troubleshoot tool. Once you’ve downloaded the troubleshooter, run the tool. After running the tool, check if you are able to access Windows Update services as well as activate Windows 10. If the problem with error code 0xd0000272 persists, however, follow the instructions provided for manual repair method three detailed below.
Another option available to individuals experiencing error code 0xd0000272 in Windows 10 is to manually disable their machine’s proxy settings. After disabling the proxy settings, remember to open the Windows Update tab to complete the activation process. See the instructions provided below to disable proxy settings.
Once you have successfully disabled your proxy settings, open Windows Update. Select the activation option to access your copy of Windows 10. If you are unable to complete the activation process, however, contact a Windows repair technician.
In today's age, free cloud storage is no longer anything exclusive and plenty of companies will offer some free amount of it in hopes that you will buy a premium plan. Among plenty of starter and free options, there are of course some that are more generous and more appealing and offer a larger quantity of free space and even some other services.
In this article, we are taking a look and recommending some of the best ones in our opinion.
First on the list is of course google with its google drive. With an amazing 15GB of free could storage just given to anyone who makes a google account this had to be the first recommendation. Also since google drive is requiring a google account you will be given all google office tools for free as well as the Gmail service. Completely free 15GB at your fingertips if you do not mind google tracking policies.
Another company on the list, with only 5GB storage seems little compared to google this entry was simply included because google Microsoft also offers you Office 365 WEB for free with skype along with their Hotmail. So all in all another full package of apps with some free storage that requires also just an account.
With the free offer of 10GB this comes as an easy recommendation, IceDrive is a cloud storage company that is not offering anything of productivity apps but it has some great features in their cloud solution like being able to see encrypted files in your cloud. All you have to do to get this 10GB of storage is to make a free account.
With an amazing 20GB of free storage, MEGA is certainly one that gives the most space for free. Sadly a few years ago it was hacked and files and user information were leaked, for that reason, it is on our last place of recommendation but if you are not worried about their security and plan just to use this as a temporary file sharing service with that amount I am sure it will fill your needs.
