VBS.Gpremier@mm

SUMMARY

VBS.Gpremier@mm is a mass-mailing worm that is written in the Visual Basic Scripting (VBS) language. When it is executed, it copies itself to the WindowsSystem folder and infects all the HTML files with the VBS.CandyLove virus.

VBS.Gpremier@mm mails itself to all the contacts in all the Microsoft Outlook Address Books. The email would have the following characteristics:
Subject: NO estimado Bill G.
Attachment: gpremier.vbs

NOTE: Virus definitions dated prior to February 7, 2003 may detect this as Bloodhound.VBS.Worm.

Protection

• Virus Definitions (LiveUpdate™ Weekly) February 12, 2003
• Virus Definitions (Intelligent Updater) February 7, 2003

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Low
• Large Scale E-mailing: Sends email to all contacts in the Microsoft Outlook Address book.

Distribution

• Distribution Level: High
• Subject of Email: NO estimado Bill G.
• Name of Attachment: gpremier.vbs
• Size of Attachment: 8,204 bytes

TECHNICAL DETAILS

When VBS.Gpremier@mm is executed, it attempts to do the following:

1. Copies itself as C:WindowsSystemGpremier.vbs.
   
2. Adds the value:
   
   gpremier    "wscript.exe c:windowssystemgpremier.vbs %"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   so that the Trojan runs when you start Windows.
   
3. Checks the value of html:  
   
   in the registry key:
   
   HKEY_CURRENT_USERsoftwaregpremier
   
   If the value is not 1, the worm writes the VBS.CandyLove virus to all the HTML files as an embedded VBScript. Then, it sets the value of html
   
   in the registry key:
   
   HKEY_CURRENT_USERsoftwaregpremier
   
   to 1, so that the HTML files are infected only once.
   
4. Checks the value of correo
   
   in the registry key:
   
   HKEY_CURRENT_USERsoftwaregpremier
   
   If the value is not 1, the worm attempts to email all the contacts in the Microsoft Outlook Address Book.
   
   The message that the worm sends is:
   
   Subject: NO estimado Bill G.
   Message Body:
   Hola que tal,
   Aqui le adjunto los precios para su funeraria.
   Attachment: gpremier.vbs
   
   Then, it sets the value of correo
   
   in the registry key:
   
   HKEY_CURRENT_USERsoftwaregpremier
   
   to 1, allowing the email routine to be performed only once.
   
5. Changes the Internet Explorer home page by modifying the Value Data of Start Page
   
   to:
   
   http:/ /www.gpremier.com.mx
   
   in the registry key:
   
   HKEY_USERS.DEFAULTSOFTWAREMicrosoftInternet ExplorerMain
   
   so that this particular Web page opens when you start Internet Explorer.
   
6. Changes the Internet Explorer window title by modifying the Value Data of Window title
   
   to:
   
   Perteneces al TecPremier
   
   in the registry key:
   
   HKEY_USERS.DEFAULTSOFTWAREMicrosoftInternet Explorer
   MainWindow title
   
   
7. Checks the value of colgar
   
   in the registry key:
   
   HKEY_CURRENT_USERsoftwaregpremier
   
   • If the value has not been set, the worm sets the value to 0.
   • If the value is equal to or greater than 10, the worm attempts to run 101 copies of C:WindowsNotepad.exe, and then sets the value to 0.
   • If the value is less than 10, the worm increases the value by 1.
     
     
8. Checks the value of borrar
   
   in the registry key:
   
   HKEY_CURRENT_USERsoftwaregpremier
   
   • If the value has not been set, the worm sets the value to 0.
   • If the value is equal to or greater than 3, the worm attempts to delete the following files:
     • All the .jpg files in the C:Windows directory.
     • All the .bmp files in the C:Windows folder.
     • All the files in the C:WindowsEscritorio folder.
     • All the files in the C:misdoc~1 folder.
       
       Then, the worm sets the value to 0.
       

If the value is less than 3, the worm increases the value by 1.

9. Copies itself using one of these file names:
• Leme.txt.vbs
• Importante.txt.vbs
• Archivo.vbs
• Juegos.vbs
• Mensaje.txt.vbs
• Solitario.vbs
  

10. Sends "www.gpremier.com.mx" as keystrokes to the active application.

Recommendations

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

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

These instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Update the virus definitions.
2. Run a full system scan and delete all the files detected as VBS.Gpremier@mm or VBS.CandyLove.
   
   NOTE: If the files are detected as infected with VBS.CandyLove, refer to the VBS.CandyLove writeup for additional removal instructions.
   
3. Reverse the changes that the worm made to the registry.
4. Reset the Internet Explorer home page

For specific details on each of these procedures, read the following instructions.


1. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:

• Running LiveUpdate, which is the easiest way to obtain the virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate), in the "Protection" section, at the top of this writeup.
• Downloading the definitions using the Intelligent Updater. The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater), in the "Protection" section, at the top of this writeup.
  
  The Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

2. Scanning for and deleting the infected files

1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
   • For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
   • For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec Corporate antivirus product is set to scan All Files."
2. Run a full system scan.
3. If any files are detected as infected with VBS.Gpremier@mm or VBS.CandyLove, click Delete.
   
   NOTE: If the files are detected as infected with VBS.CandyLove, refer to the VBS.CandyLove writeup for additional removal instructions.
   

3. Reversing the changes made to the registry

CAUTION: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type regedit, and then click OK. (The Registry Editor opens.)
3. Navigate to the key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the value:
   
   gpremier    "wscript.exe c:windowssystemgpremier.vbs %"
   
5. Navigate to and delete the key:
   
   HKEY_CURRENT_USERsoftwaregpremier
   
6. Exit the Registry Editor.
   
   

4. Resetting the Internet Explorer home page

1. Start Microsoft Internet Explorer.
2. Connect to the Internet and go to the page you want to set as your home page.
3. Click the Tools menu, and then click Internet Options.
4. In the Home page section of the General tab, click Use Current.
5. Click OK to exit.