Five of the Most Destructive Viruses Ever

by | May 10, 2019 | Habib O

Five of the Most Destructive Viruses Ever

Sometimes getting rid of a computer virus is as easy as pressing scan on your favorite antivirus software, but sometimes viruses can be much harder to get rid of. Here are five of the most destructive and widely spread computer worms and viruses in history.

5. Zeus

Zeus was Trojan horse made to infect computers and add them to a botnet which carried out criminal tasks. The most common of these tasks are usually keylogging and form grabbing. Zeus managed to infect thousands of FTP accounts and computers from major international corporations (including Amazon, Oracle, Bank of America, Cisco, and many more). In the US alone, it was estimated that more than 1 million computers were infected. The Zeus botnet was used to steal the login credentials for many accounts. The entire operation was sophisticated, involving people from around the world to smuggle and transfer cash. About $70 million were stolen and in possession of the ring. 100 people were arrested in connection with the operation.


4. Melissa

Melissa was an infected Word document that, when opened, would send itself to 50 more people in someone’s address book. It used social engineering to convince people to open it, advertising itself as a list of passwords for a pornography site. It also corrupted some files by inserting a Simpsons reference to the source code. Melissa overloaded mail servers and reportedly caused $80 million in damages. Melissa was the name of a stripper the programmer had met in Florida.


3. Code Red

Code Red was discovered in 2001 by two eEye Digital Security employees. The worm attacked machines with Microsoft IIS web server installed. Code Red was able to run entirely on memory and was almost invisible to anyone trying to find it. Once infected, it made a hundred copies of itself but due to a bug in the programming, it exponentially increased its number of copies. Then it launched a DOS attack on a few IPs, including the White House’s website. It also created a backdoor to control the machine it ran on remotely. It left behind a message on web pages it affects: “Hacked By Chinese!”. A total of 1-2 million servers were affected, causing about $2 billion in damages. It was named Code Red because the employees who found it were drinking Code Red Mountain Dew when they found it.


2. SQL Slammer

On January 25, 2003, at 6:00 AM G.M.T. SQL Slammer broke the Internet. Connectivity around the world fell through the floor. All of South Korea lost its internet and phone services. Airlines could not process tickets, and flights were cancelled. Some 911 call centers (like Seattle) were forced to use paper to log calls, and lots of connected devices went dark like bank ATMs. The few who did have Internet access had extremely slow speeds. This all happened due to Slammer, a worm that attacked SQL servers. Slammer essentially reprogrammed SQL servers to replicate itself and send copies of Slammer to other servers. This worm spread faster than any other had, infecting 75,000 servers in only 10 minutes. In the end, Slammer had infected millions of servers and caused the internet to go out for a while.



ILOVEYOU is one of the most harmful viruses in all of history, causing an estimated $10 billion in damages. It affected almost 10% of all computers connected to the internet and spread itself exponentially. It spread through emails with the subject line: ILOVEYOU. The worm used social engineering to convince the victim to open a script file that looked like a TXT file enclosing a love confession. After opened, ILOVEYOU sent itself to everyone in the users mailing list and began overwriting every file of the user’s computer with itself, making the computer essentially unbootable. The destruction this virus caused governments and large corporations to completely shut down their mailing systems out of fear of the virus spreading throughout their networks. The virus was created by Reonel Ramones and Onel de Guzman, two Filipino programmers. They were never charged with any crimes since there were no laws against creating or distributing malware.

Habib O

Self proclaimed tech enthusiast looking to expand my personal portfolio. Click my profile to find out more. PS. If you give me something i will break it.