According to a report by Sophos The worm, which exploits users who have installed SSH and not changed the default password, hunts for other vulnerable iPhones and infects them.
Users are advised to properly secure their jailbroken iPhones with a non-default password, and Sophos says the worm is not harmless, despite its graffiti-like payload:
"Accessing someone else's computing device and changing their data without permission is an offence in many countries — and just as with graffiti there is a cost involved in cleaning-up affected iPhones... Other inquisitive hackers may also be tempted to experiment once they read about the world's first iPhone worm. Furthermore, a more malicious hacker could take the code written by ikee and adapt it to have a more sinister payload."
Images of the Rick Astley wallpaper displayed on infected phones, complete with the message "ikee is never going to give you up" are published here.