Many people consider the world's most dangerous computer virus to have been unleashed back in 201, as a form of malware known as WannaCry affected nearly every country around the world.

More than this, it has a fascinating origin and ending that changed cybersecurity forever.

Computer viruses are always deadly, no matter what form they take, and it's often only the scale at which they are unleashed that determines the damage that's inflicted in the end.

Officials have revealed a terrifying new malware that spies on you during your most intimate moments as a means of 'sexploitation', and other cyberattacks have often cost businesses millions of dollars in attempts to combat the effects.

Nearly every virus out there still pales in comparison to the WannaCry ransomware attack that hit the world in May 2017, especially as almost every computer running Microsoft's Windows operating system was affected by the malware.

As shared by Cybernews on YouTube, this attack started when an unknown hacking group suspected to originate from North Korea employed an exploit developed by the US government's National Security Agency (NSA). This was exposed in a leak by The Shadow Brokers (TSB).

This exploit, known as EternalBlue, took advantage of a zero-day vulnerability in the Windows OS that allowed its user to gain access to any computers connected to a network.

The spread began in the early morning on May 12, 2017, and within just a couple of hours, it had spread to over 300,000 computers in more than 150 countries. It locked them out of their devices and demanded a ransom payment in Bitcoin in order to return access.

While Microsoft had seemingly developed and released patches that prevented computers from being affected by the EternalBlue exploit, many devices had either not installed these updates or were using older Windows operating systems that had reached their end-of-life before the updates were released.

This led them to be exposed to WannaCry, and enabled the spread that took down hundreds of thousands of computer systems across the globe.

It is estimated that anywhere between hundreds of millions to billions of dollars in damages were caused as a result of the virus that rapidly spread across the world. That’s just from less than half a day's downtime before a kill switch was discovered and activated.

23-year-old computer security researcher Marcus "MalwareTech" Hutchins was the man who came to the world's rescue, registering a kill switch that prevented computers that had already been infected from data encryption and spreading the virus any further. Hutchins effectively shut down WannaCry at 15:03 UTC, just over seven hours after the malware was unleashed.

What's staggering is that the kill switch discovered by Hutchins was already built into the virus by its creators, leaving many to wonder why it was there and if it had been included by mistake, especially as the malware was allegedly released in an unfinished state.