W97M.Hopel.A

SUMMARY

W97M.Hopel.A is a macro virus that infects Microsoft Word documents when you click Open, Close, Save, New, or Exit. This virus has many different payloads that it can execute on Exit.

If an infected document is double-clicked, the virus saves the infected document as C:WindowsCommandNt.txt.

W97M.Hopel.A also overwrites the Autoexec.bat file with a non-ASCII character.

Protection

• Virus Definitions (LiveUpdate™ Weekly) February 12, 2003
• Virus Definitions (Intelligent Updater) February 6, 2003

Threat Assessment

Wild

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

Damage

• Damage Level: Low
• Payload Trigger: Random plus multiple date triggers
• Payload: Multiple payloads, most involve renaming system files
• Deletes Files: Randomly deletes some files
• Causes System Instability: Randomly renames system files

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When a document that is infected with W97M.Hopel.A is opened, the virus infects the Microsoft Word template file, Normal.dot. After this occurs, when a clean document is opened, the virus inserts its code into the clean document.

When an infected document is double-clicked, the virus does the following:

• Saves a copy of the infected document as C:WindowsCommandNt.txt. This is a Read-only, Hidden file.
• Overwrites the Autoexec.bat file with a non-ASCII character.
• Runs one or more of its payloads. The payloads vary and may be day- or date-activated. They are described in the next section.

Payloads

October 21
If the date is October 21 of any year and an infected document is double-clicked, the virus modifies two values as shown here:

s1159 PUKKA
s2359 PUKKA

of the registry key:

HKEY_USERS.DefaultControl PanelInternational

Monday
If the day is Monday and an infected document is double-clicked, the virus may perform one, or more, or all of the following:

• Deletes the file, C:WindowsSystemEpson9.drv
• Renames the files:
  • C:WindowsSystemNetbeaui.vxd to C:WindowsSystemIuebten.vxd
  • C:WindowsCommandCommand.com to c:WindowsCommandDnammoc.com
  • C:Command.com to C:Dnammoc.com
  • C:WindowsSystemMouse.drv to C:WindowsSystemEsuom.drv
• Modifies the value as shown here:
  
  sDecimal $
  
  of the registry key:
  
  HKEY_USERS.DefaultControl PanelInternational
  
• Sets the password of the infected document to "013000"

Tuesday
If the day is Tuesday and an infected document is double-clicked, the virus may perform one, or more, or all of the following:

• Renames the files:
  • C:WindowsSystemCm8330.drv to C:WindowsSystem339mc.drv
  • C:WindowsSystemcm8330.vxd to C:WindowsSystem338mc.vxd
  • C:WindowsSystemvmm32.vxd to C:WindowsSystem23mmv.vxd
• Modifies the value as shown here:
  
  Config.Sys DOS=SINGLE
  
  of the registry key:
  
  HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionMS-DOSOptionsDOSSettings

Wednesday
If the day is Wednesday and an infected document is double-clicked, the virus may perform one, or more, or all of the following:

• Renames the files:
  • C:WindowsSystemDplay.dll to C:WindowsSystemYalpd.dll
  • C:WindowsSystemDplayx.dll to C:WindowsSystemXyalpd.dll
  • C:WindowsSystemvmm32.vxd to C:WindowsSystem23mmv.vxd
• Sets the password of the infected document to "013000"

Thursday
If the day is Thursday and an infected document is double-clicked, the virus may rename C:WindowsSystemvmm32.vxd to C:WindowsSystem23mmv.vxd.

Friday
If the day is Friday and an infected document is double-clicked, the virus may rename C:WindowsSystemSage.dll to C:WindowsSystemegas.dll.

Saturday
If the day is Saturday and an infected document is double-clicked, the virus may rename C:WindowsSystemComdlg32.dll to C:WindowsSystem23gldmoc.dll.

At random
The virus also randomly renames the files:

• C:WindowsSystemNdis.vxd to C:WindowsSystemSidn.vxd
• C:WindowsSystemNwlink.vxd to C:WindowsSystemKnilwn.vxd
• C:WindowsSystemVredir.vxd to C:WindowsSystemRiderv.vxd

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

The following 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 repair all the files detected as W97M.Hopel.A.
3. Recover the files and reset the registry values as necessary.

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 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 repairing the infected files

1. Start your Symantec antivirus software 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 W97M.Hopel.A, click Repair.

3. Recovering files and resetting registry values
Depending on which payload, if any, was activated, you may have to:

• Rename one or more files to their original file names.
• Reset one or more registry value(s).
• Restore the deleted files from a clean backup or re-install them.
• Replace the Autoexec.bat file from a clean backup if you are running Windows 95/98/Me.
  

Refer to the Technical Description section for further details on what the W97M.Hopel.A virus can do and when it performs its functions.