Happy99

Happy99, also known as the "Happy 99" or "Happy 99 Virus," is one of the earliest computer worms, which was first detected in 1999. It was distributed as an executable file that appeared to be a festive animation to celebrate the New Year. When a user executed the file, it would display a fireworks animation while simultaneously replicating itself and spreading to other users' email addresses found in the infected user's address book.