Another malicious worm hit Twitter over the weekend, days after the micro-blogging site reached near-meltdown from a technically similar attack.

This time around the danger came from clicking links contained in micro-blogging messages beginning "WTF [URL]". Last week's more serious onMouseOver problem struck when users moved their mouse cursor over an infected tweet. These messages contained hidden JavaScript code that exploited a cross-site scripting problem - in the case of the WTF worm a CSRF (cross-site request forgery) technique is in play.

The miscreants behind the latest assault set up an attack page that exploited a CSRF vulnerability in Twitter so that victims who clicked on a link posted a crude message about their supposed fondness for sex with goats, as explained in a blog post by Sophos here.

Victims included celebrity blogger Robert Scoble, but far fewer people were affected than by the much bigger onMouseOver hack.

Twitter responded to the latest attack by disabling the link and, by late on Sunday, fixing the exploit that spawned the worm. The micro-blogging service is in the process of mopping up the remaining mess by purging the dodgy tweets from infected accounts, as explained in an update on Twitter's status page here. ®