Thousands flock to 'malware museum'
An online archive of old computer malware has attracted more than 100,000 visitors since it launched four days ago.
Some of the software showed an animation or messages. Others invited the infected user to play a game.
Many of the viruses were created by "happy hackers" rather than organised criminals, said cybersecurity expert and curator Mikko Hypponen.
The malware all dates from the 1980s and 1990s.
The versions online have all been stripped of their destructive capabilities, but show the messages they would have displayed within emulator windows.
Much of the collection is mischievous and colourful in nature, but there was also more sinister malware around.
"I only chose interesting viruses," Mr Hypponen said of his picks.
His personal favourite is a virus called Casino, which overwrote a crucial part of the computer's file system but took a copy of personal files and then offered the user the opportunity to win them back in a game of Jackpot.
"Casino was a real problem," Mr Hypponen, who works at security firm F-Secure, told the BBC.
"At the time the advice was, you lose nothing by playing. In the early 1990s very few people had back-ups so you had lost your files anyway."
He said he was surprised by the number of people who felt nostalgic about the old malware.
"Most of the malware we analyse today is coming from organised criminal groups... and intelligence agencies," Mr Hyponnen added.
"Old school happy hackers who used to write viruses for fun are nowhere to be seen."