Elk Cloner has the distinction of being the first wild virus for a home computer, and was the first known computer virus. Coded by then-high-school student, Richard Skrenta, around 1982, it did not do much more than cause some annoyance by periodically displaying a message and probably did not spread much further than the computers of a few of Skrenta's friends and his math teacher. It was also completely harmless, save for causing some annoyance. The virus began spreading when Skrenta gave away copies of pirated programs with the virus on them.
When an infected disk was booted, the virus would load into the memory. It would monitor disk accesses, and upon finding an uninfected floppy, infect its boot sector. The virus will only infect 5.25 inch floppy disks, as they were the standard type of disk in 1982 and a hard drive was unlikely to even be on a computer, as operating systems and programs were loaded entirely from floppies.
Elk Cloner did not cause any deliberate harm, although overwrote its reserved tracks regardless of the contents, damaging disks not containing the standard DOS image. Typical of many early viruses, it caused annoyance: on every 50th booting the virus would display a short "poem".
Richard Skrenta often traded pirated software on disks with friends. He was well-known for using disks to pull pranks on friends, who began to distrust any disks they received from him. His disks often displayed taunting messages. Elk Cloner was the first to spread on its own.
In 2007 July, many Internet sites began reporting that the world had entered the 25th year of computer viruses, while others claimed that Creeper, created 15 to 10 years earlier than Elk Cloner was the first. Technically, Elk Cloner is the first virus, as Creeper does not require a boot sector or another file as a host, while Elk Cloner infects boot sectors. Regardless of definitions, Elk Cloner was the first virus or self-replicating program of any kind to work on a home computer.
Elk Cloner is an example of of the dangers of pirated software. The Brain virus a few years later was created for the purpose of preventing software piracy.
The poem can be sung to the tune of the "Man Show" theme song.
Richard Skrenta. Skrenta.com, Elk Cloner (circa 1982)
Associated Press. Fox News, "Hacker Marks 25th Anniversary of First Computer Virus". 2007.09.06
Dan Grabham. Tech.co.uk, Elk Cloner: 25 years since 1st computer virus 2007.07.17
Don Reisinger. CNet News, 25th anniversary of the computer virus? Not so fast. 2007.07.16
Martin Overton, IBM Global Technology Services, UK. The Virus Bulletin "The Journey So Far" 2007.09.19-21