W32.Mytob.F@mm

W32.Mytob.F@mm is a mass-mailing worm that uses it own SMTP engine to send an email to addresses that it gathers from the Windows Address Book on the compromised computer. The email has a variable subject and attachment name.

The worm also has the ability to open a back door and spread through the network by exploiting the Microsoft Windows Local Security Authority Service Remote Buffer Overflow (described in Microsoft Security Bulletin MS04-011).



Removing entries from the Hosts file
If this threat has modified the Windows Hosts file, there are two ways to remove these entries:

• Install and run the current version of LiveUpdate. This will remove only the entries that refer to Symantec domains.
• Manually edit the Hosts file and remove all the entries that the threat added.

To run the current version of LiveUpdate

1. Click download LiveUpdate.
   
   Note: If you are not reading this Web page on the computer that is getting the error notice, the address for downloading the file is:
   
   ftp://ftp.symantec.com/public/english_us_canada/liveupdate/lusetup.exe
   
   If necessary, you can type this address into the address bar of the problem computer. Changes to the Hosts file will not stop you from getting to this site.
   
   
2. Save the file to the Windows desktop.
3. Double-click the lusetup.exe icon on the desktop to install LiveUpdate.
4. Run LiveUpdate.
5. Did you see the message "LU1860: LiveUpdate has detected a potential security compromise on your computer"?
   • If you did, let LiveUpdate "Remove these entries from the hosts files" (Recommended).
     This should allow LiveUpdate to run.
   • If you did not, that was not the cause of the problem. Return to the Removal section.

To manually edit the Hosts file and remove all the entries that W32.Mytob.F@mm added

Note: The location of the Hosts file may vary and some computers may not have this file. For example, if the file exists in Windows 98, it will usually be in C:\Windows; and it is located in the C:\WINNT\system32\drivers\etc folder in Windows 2000. There may also be multiple copies of this file in different locations.


Follow the instructions for your operating system:

• Windows 95/98/Me/NT/2000
  1. Click Start, point to Find or Search, and then click Files or Folders.
  2. Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked.
  3. In the "Named" or "Search for..." box, type:
     
     hosts
     
     
  4. Click Find Now or Search Now.
  5. For each Hosts file that you find, right-click the file, and then click Open With.
  6. Deselect the "Always use this program to open this program" check box.
  7. Scroll through the list of programs and double-click Notepad.
  8. When the file opens, delete all the entries in step eight of the "Technical Details" section.
  9. Close Notepad and save your changes when prompted.
     
     
• Windows XP
  1. Click Start > Search.
  2. Click All files and folders.
  3. In the "All or part of the file name" box, type:
     
     hosts
     
     
  4. Verify that "Look in" is set to "Local Hard Drives" or to (C:).
  5. Click More advanced options.
  6. Check Search system folders.
  7. Check Search subfolders.
  8. Click Search.
  9. Click Find Now or Search Now.
  10. For each Hosts file that you find, right-click the file, and then click Open With.
  11. Deselect the Always use this program to open this program check box.
  12. Scroll through the list of programs and double-click Notepad.
  13. When the file opens, delete all the entries in step eight of the "Technical Details" section.
  14. Close Notepad and save your changes when prompted.