Top 10 Outrageous Cyberattacks In The World

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Cyberattacks using malicious software, worms, and trojans are increasing day by day. Hackers, spammers and identity thieves are seeking new ways to steal personal information, account passwords and what not?

In this post of Terminal Stack we’ll talk about 10 such cyberattacks that caused tremendous damage in the internet world.  

But with such high stakes, it requires us to be vigilant. As millions of malware apps are attacking normal users and businesses everyday. Below listed attacks are the biggest fishes in an endless sea of cybercrime.


Cryptolocker is a type of Trojan horse ransomware which first surfaced on the internet in 2013. This malware affected 250,000 PCs around the world which led to an estimated damage of around $665 million.

Creators of this virus used a worm called gameover zeus botnet to replicate and send the copies of cryptolocker across computers. Though it was easy to remove the malware from the system, the files on the user’s computer still stayed encrypted. And he/she had to pay $400 in prepaid cash or bitcoin to decrypt the files by a private key. 

top 10 cyberattacks


This is considered to be one of the most dangerous viruses ever created. As it managed to infect around 10% PCs in the world and caused a damage of almost $10 Billion.It was created by Onel de Guzman.

 It was transmitted via email message ” ILOVEYOU” that apparently no one would ignore.It contained an attachment that read Love-Letter-For-You.TXT.vbs and obviously who would not open a text like this? The moment the receiver clicked on the attachment the virus emailed itself to the contacts available in the user’s address book and overwrote files with itself making the computer unbootable. 


Mydoom spread exponentially in the year 2004 through random email addresses, becoming one of the fastest spreading worms after ILOVEYOU. It devastated the internet by instigating a distributed denial of service (DDoS) attacks. These attacks were deliberated to shut down a target website or server.

 MyDoom deceived the users by sending a personal message which no one would likely suspect “Andy, I’m just doing my job, nothing personal, sorry”. And as soon as the user clicked upon that text, the attachment executed and the virus transmitted to all the email addresses found in the user address book. This deceitful email transmission led to a tremendous loss of almost $38 Billion. 

Mydoom is still present today sending phishing emails but it’s lesser compared to 3.4 billion emails that were sent everyday back in the year 2004.

Code Red

Code Red spread across the internet in 2001. It was termed Code Red because the discoverers were drinking Code Red Mountain Dew.

Code Red targeted Microsoft IIS users. Once it entered a system it replicated itself and then launched a denial of service attack on various websites. It brought down nearly 4,00,000 servers including the white house web server ! The amusing fact about this virus is that it displayed a text “hacked by Chinese ”! which became a meme later on.

Code Red caused over $2 billion loss.



Zeus is a close fifth among the list of worst computer viruses ever created. With nearly $100 million in estimated damages. A whitepaper by unisys stated that it accounted for almost 44% of all banking malware attacks. 

It mainly spread through drive-by downloads or phishing scams.The main purpose of Zeus botnet was to transfer money to secret bank accounts, steal victims sensitive bank details and funds. Zeus caused a documented damage of $70 millions.


Sasser was a windows worm that spread on the network servers in 2004. It was created by software engineer Sven Jaschan, who’s also known to create the Netsky worm. This worm was unstoppable as it looked for other vulnerable systems once it entered the victim’s computer.

 It’s effects were incredibly destructive as it affected Local Security Authority Subsystem Service (LSASS) which keeps a check on the safety policy of local accounts causing PCs to slow down or crash making it hard to reset until the power supply is stopped. It propagated to other machines and infected them automatically causing DDOS attacks. 


Melissa was created by David L. Smith in 1999. It was considered to be the most dangerous virus which sent NSFW pics of itself across the internet. It spread as an infected word document sent through email claiming to contain passwords of pornographic sites. When people opened the document it sent itself to the first 50 contacts in the user’s address book. Thus interrupting email services of the government and business corporation.

The virus was not created for the purpose of stealing passwords or money but did a lot of damage nevertheless, it reportedly caused a damage of $80 million.


Stuxnet is an example of a virus believed to be created for cyberwarfare. It was first uncovered in 2010, developed by US and Israeli government engineers to disrupt Iran’s nuclear program.

Stuxnet spread via USB sticks and Microsoft Windows computers. The main purpose of this worm was to look for a peculiar programmable logic controller(PLC) made by siemens. These control systems were responsible for running all types of automated processes in chemical plants, factories, oil refineries and nuclear power plants. The Stuxnet worm infected over 200,000 devices causing physical damage to more than 1,000 machines. 


Conficker, also known as downup and downadup is a windows worm that hit the world in 2008. This malware instigated more than 9 million computers around the world.

It is one of the most destructive viruses to ever surface causing an overall damage of $9 billion.The worm works by utilizing the vulnerable  network service, once it enters a system it obstructs access to windows updates and other antivirus sites, turns off certain services and blocks user accounts. It also installs a ransomware which makes the computer a botnet slave.


Windows machines dominate the market in contracting virus attacks. Yet having a mac does not guarantee your security. Shlayer trojan was responsible for almost 30% of mac attacks. 

This virus disguised itself as adobe flash player and ran unwanted ads, downloaded corrupted applications. Which led to system infections and caused many glitches.


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