W32.HLLW.Merkur.E@mm

SUMMARY

W32.HLLW.Merkur.E@mm is a mass-mailing worm that uses Microsoft Outlook to send itself to all the contacts in the Outlook Address Book. It also attempts to spread through the KaZaA, KaZaA Lite, Bearshare, and eDonkey file-sharing networks, as well as through mIRC.

The email message has the following characteristics:

Subject: (one of the following)
Free Virus Remover.
Windows Update (Build: win1.19001281)
Email Virus Remover.

Message:
Install/Update: Please run the attatchment to Install/Update your software, The program will scan for any Infected Files then continue to install/update. Regards, Bill Hanes - Nakitomi Corp.

Attachment: AVUpdate.exe

This worm is written in the Microsoft Visual Basic programming language and is compressed with UPX.

Protection

• Virus Definitions (LiveUpdate™ Weekly) June 28, 2003
• Virus Definitions (Intelligent Updater) June 28, 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
• Large Scale E-mailing: Sends itself to all contacts in the Outlook Address Book.
• Modifies Files: C:Program FilesmIRC32script.ini C:Program FilesmIRCscript.ini C:mIRC32script.ini C:mIRC32script.ini

Distribution

• Distribution Level: High
• Subject of Email: Subject line is one of the following: Free Virus Remover. Windows Update (Build: win1.19001281). Email Virus Remover.
• Name of Attachment: AVUpdate.exe
• Size of Attachment: 18,944 bytes
• Shared Drives: Attempts to spread through the KaZaA, KaZaA Lite, Bearshare, and eDonkey file-sharing networks, as well as through mIRC.

TECHNICAL DETAILS

When W32.HLLW.Merkur.E@mm runs, it does the following:

1. Copies itself as the following:
   
   C:AutoExec.exe
   C:WindowsNotepad.exe
   C:WindowsTaskman.exe
   C:WindowsScreensaver.exe
   C:WindowsSystemAVupdate.exe, whose attribute is set to read_only and hidden
   C:Program FilesKazaaMy Shared FolderHotmail Hacker.exe
   C:Program FilesKazaaMy Shared FolderXP Key Patch.exe
   C:Program FilesKazaa LiteMy Shared FolderHotmail Hacker.exe
   C:Program FilesKazaa LiteMy Shared FolderXP Key Patch.exe
   c:Program FilesBearshareSharedHotmail Hacker.exe
   C:Program FilesBearshareSharedXP Key Patch.exe
   C:Program FileseDonkey2000IncomingHotmail Hacker.exe
   C:Program FileseDonkey2000IncomingXP Key Patch.exe
   C:My Shared FolderHotmail Hacker.exe
   C:My Shared FolderXP Key Patch.exe
   
   
2. Adds the value:
   
   "Swf32"="C:WindowsAVupdate.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   
3. Creates a Script.ini file in one of the following folders, if they exist:
   
   C:Program FilesmIRC32
   C:Program FilesmIRC
   C:mIRC32
   C:mIRC
   
   The worm uses this Script.ini file to send a copy of itself to other mIRC users. The filename is Screensaver.exe.
   
   
4. Creates a file, C:Mercury.scr, which is not an executable file and not viral by itself.
   
   
5. Uses Microsoft Outlook to send itself to all the contacts in the Outlook Address Book.
   The email message has the following characteristics:
   
   Subject: (one of the following)
   Free Virus Remover.
   Windows Update (Build: win1.19001281)
   Email Virus Remover.
   
   Message:
   Install/Update: Please run the attatchment to Install/Update your software, The program will scan for any Infected Files then continue to install/update. Regards, Bill Hanes - Nakitomi Corp.
   
   Attachment: AVUpdate.exe

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. Disable System Restore (Windows Me/XP).
2. Update the virus definitions.
3. Run a full system scan and delete all the files detected as W32.HLLW.Merkur.E@mm.
4. Delete the value that was added to the registry.
5. Find and delete the file C:Mercury.scr.
6. Restore the files from a clean backup, if necessary.

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

1. Disabling System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

• "How to disable or enable Windows Me System Restore"
• "How to turn off or turn on Windows XP System Restore"

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455.

2. 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).
• 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).
  
  The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. 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 W32.HLLW.Merkur.E@mm, click Delete.

4. Deleting the value that was added to the registry

CAUTION: Symantec strongly recommends that you back up the registry before making 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
   
   Then click OK. (The Registry Editor opens.)
   
   
3. Navigate to the key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
4. In the right pane, delete the value:
   
   "Swf32"="C:WindowsAVupdate.exe"
   
   
5. Exit the Registry Editor.

5. Finding and deleting the file C:Mercury.scr
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, or copy and paste, the filename, Mercury.scr.
  4. Click Find Now or Search Now.
  5. Delete the displayed files.
  
  
• Windows XP
  1. Click Start, and then click Search.
  2. Click All files and folders.
  3. In the "All or part of the file name" box, type, or copy and paste, the filename, Mercury.scr.
  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. Delete the displayed files.

6. Restoring files from a clean backup
Restore the following files from a clean backup, if necessary:

• C:WindowsNotepad.exe
• C:WindowsTaskman.exe
• C:Program FilesmIRC32script.ini
• C:Program FilesmIRCscript.ini
• C:mIRC32script.ini
• C:mIRCscript.ini