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  3. W32.Mytob.K@mm

W32.Mytob.K@mm

Risk Level 2: Low

Discovered:
March 24, 2005
Updated:
February 13, 2007 12:35:46 PM
Also Known As:
Net-Worm.Win32.Mytob.j [Kasper, W32/Mytob.gen@MM [McAfee], W32/Mytob-F [Sophos], WORM_MYTOB.O [Trend Micro]
Type:
Worm
Systems Affected:
Windows 2000, Windows 95, Windows 98, Windows Me, Windows Server 2003, Windows XP


W32.Mytob.K@mm is a mass-mailing worm with back door capabilities. The worm uses its own SMTP engine to send email to addresses that it gathers from the compromised computer. The worm also spreads by exploiting the Microsoft Windows Local Security Authority Service Remote Buffer Overflow (as 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 the worm 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 ten 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 ten of the "Technical Details" section.
    14. Close Notepad and save your changes when prompted.


Antivirus Protection Dates

  • Initial Rapid Release version March 25, 2005
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version March 25, 2005
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date March 25, 2005
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Threat Assessment

Wild

  • Wild Level: Low
  • Number of Infections: 0 - 49
  • Number of Sites: More than 10
  • Geographical Distribution: Low
  • Threat Containment: Easy
  • Removal: Moderate

Damage

  • Damage Level: Medium

Distribution

  • Distribution Level: High
Writeup By: Masaki Suenaga

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