W32.Sobig.E

This worm propagates via network shares and via email using its own SMTP engine. It gathers its target email addresses from files with the extensions:
WAB, DBX, HTM, HTML, EML, TXT

From field is such that a different email
address appears instead of the email account it uses to send the messages. It can use
support@yahoo.com, an email address that it has obtained from the computer, or the user
name and the domain of the currently logged on user.