Description
W32/Bagle-O is an email worm which sends itself via its own SMTP engine to addresses harvested from your hard disk. The worm searches for files with the following extensions:
WAB, TXT, MSG, HTM, SHTM, STM, XML, DBX, MBX, MDX, EML, NCH, MMF, ODS, CFG, ASP, PHP, PL, ADB, TBB, ***, XLS, OFT, UIN, CGI, MHT, DHTM, JSP.
When run the worm copies itself to the Windows system folder using the name winupd.exe.
Note that W32/Bagle-O is also a parasitic virus which infects EXE files already
present on your hard disk (infected files are detected as W32/Bagle-N). If you run an infected program the worm file will reappear, just as if you had opened an infected email attachment. Be sure to replace or to disinfect files infected in this way to prevent winupd.exe from reappearing. (See the Recovery section below.)
W32/Bagle-O adds the value:
winupd.exe = <SYSTEM>\winupd.exe
http://www.sophos.com/virusinfo/analyses/w32bagleo.html
Type
Win32 worm
Description
W32/Bagle-O is an email worm which can also infect EXE files through a parasitic method.
A more detailed description will be posted here shortly.
http://www.sophos.com/virusinfo/analyses/w32bagleo.html

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