A worm that installs a ‘Safety Browser’ and plays screeching music is circulating via IM.

The annoyance starts with a link apparently sent by a friend in Yahoo’s IM program.

IM security company FaceTime Communications described the malware, which it calls “yhoo32.explr”,

The malware infects the PC with two elements. The first element is a web browser called “Safety Browser.” This stand-alone application has no uninstaller and disguises itself with an Internet Explorer logo in some instances. The application also hijacks the personal homepage in Internet Explorer and points users to Safety Browser’s homepage (demoplanet.tv). The hijack also plays looped music that cannot be stopped when the user starts up the PC or Safety Browser. The second element is the self-propagating worm. This worm installs an .exe file that spreads the infection through Yahoo Messenger to everyone on the Contacts List.

as “insidious” in a security advisory last week.

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’s permission.

The bug also hijacks Internet Explorer’s home page, directing users to the Safety Browser’s site.

After it is launched, the worm sends itself to others on the user’s instant-messaging contact list.

The malware is engineered to overwrite instant messages typed by a user, the infected message can be changed on the fly, the company said.

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