Virus writers have disguised a malicious worm as a screensaver promising to make fun at the expense of former US president Bill Clinton.

Caric-A, which is spreading on the Internet to a modest extent, normally arrives in an email with the subject "bill caricature" and an attachment named "cari.scr".

Meanwhile, the malicious payload activates, resulting in the worm forwarding itself to everyone listed in the victim's Outlook address book. If activated between 8am and 9am, it also attempts to delete files from root directories and with the extensions .SYS, .VXD, .OCX and .NLS, according to an analysis by Sophos.

As usual, Mac and Linux users are immune from the bug.

Text at the end of the email says "No viruse [sic] found", and quotes AV company MCAFEE.COM, to give the impression that it has been scanned and found to be clean.

Antivirus vendors are in the process of updating virus signatures to spot the malicious code and protection is now largely in place. ®

Related stories

Britney Spears virus fails to chart
Anna Kournikova virus spreading like wildfire
Anna Kournikova bug drops harmlessly onto the Net
Kournikova virus kiddie gets 150 hours community service
2001: vintage year for virus infections
Rise in viruses within emails outpacing growth of email
Hybrid viruses set to become bigger threat
Users haven't learned any lessons from the Love Bug
Virus toolkits are s'kiddie menace