Sobig.E is sent via e-mail, compressed in a zip file, creating an added danger as to date, there have been few viruses that have propagated in this way and many users may not have the option to scan this particular type of compressed file enabled in their antiviruses.
Sobig.E infects Win9x, ME, NT, 2000 and XP systems. It is sent out, using its own SMTP engine, to addresses it finds in all directories in files on the infected system with the following extensions: .TXT, .EML, .HTM*, .DBX, .WAB.
The e-mail containing Sobig.E has the following characteristics:
Possible subjects include:
Message text: Please see the attached zip file for details.
Sobig.E creates two files in the affected computer, one called "%windir%\winssk32.exe", which contains the worm's code, and the other called "msrrf.dat". It also creates two keys in the Windows registry.