Research experts at FaceTime Security Labs have identified and reported a new threat affecting Yahoo! Messenger. FaceTime researchers confirmed that a self-propagating worm, named yhoo32.explr, installs "Safety Browser" and hijacks the Internet Explorer homepage, leading users to a site that puts spyware on their PCs. Because Safety Browser uses the IE icon, users can easily mistake it for Internet Explorer. This is the first recorded incidence of malware installing its own web browser on a PC without the user's permission.
The self-propagating worm spreads the infection to all contacts in Yahoo! Messenger by sending a website link that loads a command file onto the user's PC and installs Safety Browser. This spam over instant messaging (IM) is called spim. IM applications and protocols are an increasingly popular vector to distribute malicious files and executables.
"This is one of oddest and more insidious pieces of malware we have encountered in years," commented Tyler Wells, senior director of research at FaceTime Security Labs. "This is the first instance of a complete web browser hijack without the user's awareness. Similar 'rogue' browsers, such as 'Yapbrowser,' have demonstrated the potential for serious damage by directing end-users to potentially illegal or illicit material. 'Rogue' browsers seem to be the hot new thing among hackers."
The India research arm of FaceTime Security Labs discovered the threat in a "honeypot," a trap they set to detect viruses, worms, spyware and other threats. Commentary on this threat by FaceTime Security Labs researcher Chris Boyd can be found on the Greynets Blog, at blog.spywareguide.com/. FaceTime Security Labs is the threat research division of IM and Greynet security leader FaceTime Communications.
Threat name: yhoo32.explr
Threat type: Browserware and worm
Who is affected: Users of Yahoo! Messenger
Additional Information: 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.
FaceTime's RTGuardian and GEM customers are protected from this exploit if they have auto-update features enabled. FaceTime's X-Cleaner customers should download the latest update and scan their PC.