MyDoom.s prevention and cure

This mass-mailing virus appears to contain photos but actually attempts to install a backdoor Trojan horse.

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By Robert Vamosi
CNET Reviews

A variation of the MyDoom virus appears to be e-mail containing photographs. MyDoom.s (w32.MyDoom.s@mm, also known as MyDoom.m (Norman), MyDoom.q (Symantec), MyDoom.r (Panda), and Ratos (Trend Micro)) is a mass-mailing worm that uses its own SMTP engine to send out copies of itself to addresses harvested from the infected PC. It spoofs the return address, making it hard to trace infected machines, and attempts to download a backdoor Trojan horse from one of two sites on the Internet. MyDoom.s does not affect Linux, Mac, or Unix systems. Because MyDoom.s spreads via e-mail, opens a remote access backdoor on infected PCs, and could damage system files, this worm rates a 6 on the CNET/ZDNet Virus Meter.

How it works
MyDoom.s arrives as an attachment with the following characteristics:

Subject : photos
Body : LOL!;))))
Attachment : photos_arc.exe

If the attachment is opened, MyDoom.s adds the file rasor38a.dll to the Windows folder and the file winpsd.exe to the system directory. It also makes the following system Registry changes:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\ Explorer\ComDlg32
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\ Run "winpsd" = C:\WINDOWS\System32\winpsd.exe

Once executed, MyDoom.s attempts to download a backdoor Trojan horse from either or

If you receive MyDoom.s, do not open the attached file. The best way to prevent infection is to make sure that your antivirus signature files are current. Also, a personal firewall will prevent the virus author from gaining remote access to your PC.

A few antivirus software companies have updated their signature files to include this worm. This will stop the infection upon contact and in some cases will remove an active infection from your system. For more information, see Computer Associates, F-Secure, McAfee, Norman, Panda, Sophos, Symantec, and Trend Micro.

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