The OSX/Leap-A worm spreads via the iChat instant messaging system, forwarding itself as a file called latestpics.tgz to contacts on the infected users' buddy list. When the latestpics.tgz archive file is opened on a computer it disguises its contents with a JPEG graphic icon in an attempt to fool people into thinking it is harmless.
The worm uses the text "oompa" as an infection marker in the resource forks of infected programs to prevent it from reinfecting the same files.
"Some owners of Mac computers have held the belief that Mac OS X is incapable of harboring computer viruses, but Leap-A will leave them shellshocked, as it shows that the malware threat on Mac OS X is real," said Graham Cluley, senior technology consultant for Sophos. "Mac users shouldn't think it's okay to lie back and not worry about viruses."
Experts at Sophos are continuing to examine OSX/Leap-A and will issue further information shortly. Sophos customers have been automatically protected against the worm since 12:25 GMT, 16 February 2006.
"This is the first real virus for the Mac OS X platform," continued Cluley. "Apple Mac users need to be just as careful running unknown or unsolicited code on their computers as their friends and colleagues running Windows."
First Mac OS X virus discovered
Posted on Thursday, February 16 2006 @ 19:15 CET by Thomas De Maesschalck