The scale of the Mirai attack showed just how easily artificial
infections can spread. Another high-profile example would emerge a
few months later, on 12 May 2017, when a piece of software called
‘WannaCry’ started holding thousands of computers to ransom. First
it locked users out of their files, then displayed a message telling
users they had three days to transfer $300 worth of Bitcoin to an
anonymous account. If people refused to pay up, their files would be
permanently locked. Wanna Cry would end up causing widespread
disruption. When it hit the computers of the UK National Health
Service, it resulted in the cancellation of 19,000 appointments. In a
matter of days, over a hundred countries would be affected, leading
to over $1bn worth of damage.[3]
Unlike outbreaks of social contagion or biological infections, which
may take days or weeks to grow, artificial infections can operate on
much faster timescales. Outbreaks of malicious software – or
‘malware’ for short – can spread widely within a matter of hours. In
their early stages, the Mirai and WannaCry outbreaks were both
doubling in size every 80 minutes. Other malware can spread even
faster, with some outbreaks doubling in a matter of seconds.[4]
However, computational contagion hasn’t always been so rapid.
T to spread ‘in the wild’ outside of a
laboratory network started as a practical joke. In February 1982,
Rich Skrenta wrote a virus that targeted Apple II home computers. A
fifteen-year-old high school student in Pennsylvania, Skrenta had
designed the virus to be annoying rather than harmful. Infected
machines would occasionally display a short poem he’d written.[5]
The virus, which he called ‘Elk Cloner’, spread when people
swapped games between computers. According to network scientist
Alessandro Vespignani, most early computers weren’t networked, so
computer viruses were much like biological infections. ‘They were
spreading on floppy disks. It was a matter of contact patterns and
social networks.’[6] This transmission process meant that Elk Cloner
didn’t get much further than Skrenta’s wider friendship group.
Although it reached his cousins in Baltimore and made its way onto