The Creeper virus was an experimental, self-replicating program written by Bob Thomas at BBN in 1971. It was designed not to damage but to demonstrate a mobile application. It is generally accepted to be the first computer virus. although the notion of a computer virus didn't exist in 1970s. Creeper infected DEC PDP-10 computers running the TENEX operating system. Creeper gained access via the ARPANET and copied itself to the remote system.