Threat Explorer

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VBS.Mill.F

VBS.Mill.F

Discovered:
31 January 2001
Updated:
13 February 2007
Also Known As:
VBS/Mill

VBS.Mill.F is a variant of VBS.Mill. It is a is a Visual Basic Script worm that copies itself to several folders on the hard disk. The worm uses Microsoft Outlook to spread itself. The worm also drops an mIRC configuration file that is used to spread itself. The worm overwrites .vbs files in specific folders.

Antivirus Protection Dates

  • Initial Rapid Release version 13 February 2001
  • Latest Rapid Release version 08 August 2016 revision 023
  • Initial Daily Certified version 13 February 2001
  • Latest Daily Certified version 09 August 2016 revision 001
  • Initial Weekly Certified release date pending
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When VBS.Mill.F is executed, the worm does the following:
  1. It copies itself to the following locations:
    • C:\SeasonGreeting.txt.vbs
    • C:\My Documents\SeasonGreeting.txt.vbs
    • C:\Windows\SeasonGreeting.txt.vbs
    • C:\Windows\System\SeasonGreeting.txt.vbs
    • C:\ProgramFiles\SeasonGreeting.txt.vbs
    • C:\Windows\Samples\WSH\SeasonGreeting.txt.vbs
    • C:\Windows\System\SeasonGreeting\SeasonGreeting.txt.vbs
  2. The worm overwrites all files that do not have the .vbs extension in following locations:
    • C:
    • C:\My Documents

      The overwritten files retain the same file name, but the file extension is changed to .txt, followed by 100 blank spaces, followed by .vbs. For example, the file Letter to Linda. doc would be changed to:

      Letter to Linda. doc.txt (100 blanks) .vbs

      Because this long extension will not display properly on the Windows desktop or in Windows Explorer, the file will appear to be a text file.
  3. It changes several registry keys. This affect the system as follows:
    • Mouse and keyboard properties are changed.
    • Desktop pattern is changed to Circles.bmp.
    • You can no longer open .exe, .mp3, jpg, .gif, or .mpg files.
    • The proxy setting is changed to "proxy.SeasonGreeting.com.sg:8080"
  4. It creates the following .bat file and causes it to be run at startup:

    C:\Windows\System\SeasonGreeting\SeasonGreetingAutoExec.bat

    This .bat file attempts to delete .txt, .zip, .exe, .mp2 and .mp3 files in the following locations:
    • C:\My Documents
    • C:\My Music
    • C:\My Documents\My Music
  5. It drops the mIRC configuration file C:\Mirc\Script.ini. If you run mIRC after infection with the worm, mIRC will send the SeasonGreeting.jpg.vbs file others who are connected to the server.
  6. It sends email to all addresses in Microsoft Outlook address book, with itself as an attachment:

    Subject:

    You got a Christmas E-Card from you friend!

    Message:

    Wishing you a Merriest Christmas!!
    You got a Christmas Electronic Card from you friend!!
    Please open attachment to view E-Card
    E-Card Brought to You By f0xCiTY

    Attachement:

    SeasonGreeting.txt.vbs


Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

To remove the worm:
  1. Run LiveUpdate to make sure that you have the most recent virus definitions.
  2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
  3. Delete files detected as infected by VBS.Mill.F, VBS.Mill.F.ini and VBS.Mill.F.bat.
  4. Restore the Web browser proxy setting, mouse and keyboard settings, and restore your original desktop pattern.

    NOTE: These changes can all be done within Windows; you need not edit the registry. See your Windows documentation for information on how to do this.
  5. Any files that were overwritten by the worm must be restored from backups.


Writeup By: Kaoru Hayashi