The worm, dubbed Yhoo32.explr by IM security vendor FaceTime Communications on Friday and "Browaf" by Symantec on Monday, is installed when Yahoo users click on a malicious link embedded within an instant message. Yhoo32.explr downloads and installed the so-called "Safety Browser," which adds an IE-like icon to the desktop, and when used, takes the unsuspecting to sites where their PCs are infected with adware and spyware. The worm also changes the home page of IE to point to Safety Browser's site. To complicate things, Safety Browser doesn't post an Uninstall option in Windows' Add or Remove Programs Control Panel applet. The second element is the self-propagating worm. The worm propagates by inserting a link into existing Messenger conversations on an infected PC. When an infected user initiates or joins a conversation, a link is inserted at random points in the conversation.