Like other recent worms, Winevar takes advantage of a well-known Iframe vulnerability is Microsoft's Internet Explorer and Outlook E-mail clients. The flaw makes it possible for such worms and viruses to open HTML formatted messages and execute them without user activation.
Once Winevar is on a system, it installs a virus similar to Funlove that tries to turn off installed antivirus software. According to antivirus vendor F-Secure Corp., Winevar also continuously tries to download the Symantec home page to a temporary file. "This might create a denial-of-service attack in case the worm becomes widespread," F-Secure writes in an advisory published Wednesday.
Infected messages may contain the following in the subject line:
Re: AVAR (Association of Anti-Virus Asia Researchers)N`4 %RegisteredOrganization% N`4 Trand Microsoft Inc.
Experts believe the worm's release may have been timed with the AVAR conference held last week in Seoul. The second subject line captures the "RegisteredOrganization" key in the Windows System Registry. If that key isn't present in the registry, the third option may be used by the worm.
When an infected computer is booted, a dialogue box titled "Make a fool of oneself" appears with the text "What a foolish thing you have done." If the "OK" button is pushed, all files on the computer system that are not open will be deleted.
Users are urged to update their antivirus software for the latest signatures. Also, users may want to ensure that their systems have been updated to include Microsoft's critical updates and patch the ActiveX vulnerability used by this worm. These can be found here.