Two new Twitter security threats have been revealed, as users of the micro-blogging site appear to be increasingly targeted for malware attacks.

Sophos brings news that Guy Kawasaki's Twitter account has been used to spread malware that targets both Windows and Mac users.

Hackers posted a message on Kawasaki's Twitter page including a link which claimed to offer a free sex video of Leighton Meester, star of "Gossip Girl".

As you might guess, following through on the lurid lure will result in nasty malware on your computer, with the Sophos video above taking you through the process.

Meanwhile Symantec's Security Response team has detected a wave of fake Twitter invitations that come carrying a mass-mailing and malicious worm.

The messages look as if they've come from a Twitter account but contain a zip file attachment, that, when opened does all kinds of horrible things to your poor PC.

Both companies are advising caution, and of course, to make sure your security software is up-to-date to protect against the ever-changing malware threats.