Since this story was originally posted, it has been updated to correct the description of the Yahoo messaging worm\u2019s effects.Malware writers have created a new worm that installs a new browser and\u00a0plays screeching music.The annoyance starts with a link apparently sent by a friend in Yahoo\u2019s instant messaging program.Instant messaging security company FaceTime Communications described the malware, which it calls "yhoo32.explr," as "insidious" in a security advisory Friday.When the link is clicked, a worm installs the so-called "Safety Browser," a program that leads the user to pages mined with adware and viruses, FaceTime said. The Safety Browser uses an Internet Explorer logo to make it look more legitimate.Malware spread through instant messaging programs is on the rise. However, FaceTime said this malware appeared to be the first to install a browser without the user\u2019s permission.The bug also hijacks Internet Explorer\u2019s homepage, directing users to the Safety Browser\u2019s website.After it is launched, the worm sends itself to others on the user\u2019s instant messaging contact list. The malware is engineered to overwrite instant messages typed by a user, FaceTime said. The infected message can also be changed on the fly, the company said.The screeching music, however, is blocked by Microsoft\u2019s Windows XP Service Pack 2, FaceTime said.FaceTime has posted screenshots of the infection process on its blog.-Jeremy Kirk, IDG News ServiceCheck out our CIO News Alerts and Tech Informer pages for more updated news coverage.