Called MacSimpson, the worm arrives attached to an e-mail message promising recipients access to secret episodes of "The Simpsons." Instead, those who open the attachment get a typical mass-mailing worm that uses AppleScript to infect Macs using OS 9.0 or 9.1 and sends itself across the Internet.
"No operating system is immune from viruses; it's just people taking the time to write them," said Susan Orbuch, spokeswoman for antivirus software company Trend Micro.
At present, Trend Micro has not had any reports of Mac users infected by the virus, Orbuch said. Rival security company Symantec received a handful of reports.
The worm is not very malicious but could clog networks with the sheer volume of e-mail it produces. The worm appears in an e-mail with the subject line, "Secret Simpsons Episodes!" and this message:
Hundreds of Simpsons episodes were just secretly produced and sent out on the Internet, if this message gets to you, the episodes are enclosed on the attachment program, which will only run on a Macintosh. You must have system 9.0 or 9.1 to watch the hilarious episodes, in high quality. Just download and open it.
From, (a friend's name)
-- To get random signatures put text files into a folder called "Random Signatures" into your Preferences folder.
The actual virus is in the attached file named "Simpsons Episodes." If the e-mail recipient opens the attachment, the computer worm will execute, launching a program written in AppleScript to open a copy of the Outlook Express or Entourage e-mail programs in the background and send a copy of the worm and message to everyone in the person's address book.
The worm also copies itself to the Startup Items folder. If the computer user tries to quit either e-mail program while the worm is active, the application will relaunch.
The worm appears to also delete all messages from the "sent items" folder, which are moved to the "deleted" folder. They can be recovered from there.