VBS.Davinia.B

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Discovered: February 07, 2001
Updated: February 13, 2007 11:53:30 AM
Type: Worm, Macro


VBS.Davinia.B is an email worm that mails a message written in HTML to everyone in your Microsoft Outlook address book.

The message has no subject line and appears blank, but it contains HTML code that starts Internet Explorer and attempts to download and open a Microsoft Word 2000 document.

NOTE : The Word 2000 document has been removed from the Web server, so it cannot be downloaded, and the worm no longer operates properly.

The Word 2000 document contains a macro that does the following:

  1. Performs the mass mailing using Outlook.
  2. Creates a Visual Basic Script (VBS) file on the computer.
  3. The VBS file is executed after the computer is restarted; it then overwrites and renames all files on the local and mapped drives.

Because the infectious Word 2000 document no longer exists on the Web server, the worm will no longer do this. Also, the worm will not run if you have patched a security hole in Microsoft Office 2000 products. More information regarding this security hole can be found at:

http://www.microsoft.com/technet/security/bulletin/ms00-034.asp

The Word 2000 document is detected as W2KM.Davinia.B.
The VBS file is detected as VBS.Davinia.B.
The overwritten files are detected as HTML.Davinia.B.dam.
The email HTML message is detected as HTML.Davinia.B.

Antivirus Protection Dates

  • Initial Rapid Release version February 07, 2001
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version February 07, 2001
  • Latest Daily Certified version September 28, 2010 revision 036

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.


Technical Description


The worm arrives as an HTML email message. The subject and the body appear blank. The worm can only properly operate if you are using Microsoft Outlook without the Office 2000 UA Control patch. When reading the message, the HTML code will launch Internet Explorer. Internet Explorer will attempt to download and open a Word 2000 document.

The Word 2000 document contains a macro, which does the following:

  1. Creates the \Windows\System\Littledavinia.vbs file.
  2. Adds the value:

    Davinia         \Windows\System\Littledavinia.vbs

    to the following registry key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

    This causes the file to be run when Windows starts.
  3. The macro sends an HTML email message to all contacts in the Microsoft Outlook address book. This is recorded in the registry so that they are not emailed again.
  4. The next time that the computer is restarted, the VBS file is executed. The VBS file first modifies the start page of Internet Explorer.
  5. It then adds the value:

    Davi        littledavinia.html

    to the following key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  6. The worm searches for all files on local and mapped drives and overwrites the files with HTML code. The HTML code displays a message that is customized with your name and email address.
  7. The worm also creates the file \Windows\System\Littledavinia.html with the same code. This is executed the next time Windows is restarted.


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.


Removal


To recover from this infection you need to:

  • Edit the registry \Run key to remove the values that refer to littledavinia.
  • Scan for viruses and delete infected files.
  • Replace overwritten files.

See the following sections for detailed instructions.

To edit the registry:

CAUTION : We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.
  1. Click Start, and click Run. The Run dialog box appears.
  2. Type regedit and then click OK. The Registry Editor opens.
  3. Navigate to the following subkey:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, look for the following values:

    Davinia         \Windows\System\Littledavinia.vbs
    Davi            littledavinia.html
  5. Select one, press Delete, and then click Yes to confirm. Repeat for the other one.
  6. Click Registry, and click Exit to save the changes and close the Registry Editor.

To scan for viruses and delete infected files:
  1. Start Norton AntiVirus (NAV), and make sure that it is set to scan all files.
  2. Run a full system scan.
  3. Delete any files that are detected as infected with Davinia.B.

To replace overwritten files:
Files that have been overwritten must be restored from backup, or in the case of program files, reinstalled. If Norton Utilities is installed and the Norton Protected Recycle Bin is enabled, you may be able to recover files using the restore function.


Writeup By: Douglas Knowles