According to researchers at anti-virus vendor Sophos, the new worm was discovered this past weekend. It uses a number of different subject headers to entice recipients to open it, including 'Oh my God,' 'Hi, it's me,' 'Well, surprise?!' and 'Bad Gateway.'
Users launching the attached file will trigger the virus to harvest email addresses found on computer hard drives. The worm then forwards itself on to the list of contacts.
This variant has a couple of unique attributes. In addition to sending itself in German if it determines it is being sent to a German email address, the worm also includes a message at the bottom of forwarded emails noting it has already been virus scanned and has been found to be clean.
Further details about Sober-F can be found at: http://www.sophos.com/virusinfo/analyses/w32soberf.html