While discussing the first-known malware, the Morris worm often comes to mind. However, the roots of malware reach back roughly fifteen years earlier. In 1971, Bob Thomas pioneered the concept with the creation of the first computer worm, "Creeper." This experimental program demonstrated the capability of a computer program to replicate and spread across other computers. Notably, Creeper didn't cause any data damage. Its impact was limited to displaying a message on the teletype that read, "I'M THE CREEPER: CATCH ME IF YOU CAN.”

In 1988, a computer program, known as the Morris Worm was unleashed from MIT, infecting around 60,000 internet-connected computers. It was created by Cornell University student Robert Tappan Morris. The worm exploited vulnerabilities in Unix sendmail, buffer overflow in the finger network service, lax network logins, and weak passwords. Over a few days, it infected an estimated 6,000 computers, proving difficult to remove as it kept reinfecting the computers. The aftermath included removal costs ranging from $200 to $53,000 per installation. Morris faced three years' probation, 400 hours of community service, and a $10,050 fine after appeals. Quite a journey for a worm!

In the realm of cyber threats, Zeus is a modern Trojan horse that targets Microsoft Windows. This malware disguises itself as a harmless program, while in fact stealing banking information, through tactics like keylogging and form grabbing. What makes Zeus challenging is its adept evasion of the most sophisticated antivirus measures. In 2009, it claimed the title of the largest internet botnet, infecting 3.6 million PCs in the U.S.

Ever heard of digital bandits holding your files hostage? That's ransomware for you! a sneaky type of malware that locks away your personal data until you pay up. Some versions keep it simple, just blocking your system. The trickier versions use a fancy technique called cryptoviral extortion. They encrypt your files, making them off-limits, and then demand a ransom to spill the secret code. WannaCry is one of the most popular ransomwares that targets Windows users and demand payments in Bitcoin. Europol called it unprecedented, infecting 200,000 computers in 150 countries.