W32.HLLW.Antinny.G

SUMMARY

The W32.HLLW.Antinny.G worm is a variant of W32.HLLW.Antinny. It spreads using the Winny file-sharing network.

The worm steals personal information, including name, email and files, and sends it to a file-sharing network.

The worm has the Notepad icon or a Windows folder icon.

Definitions dated prior to March 19, 2004 may detect this threat as W32.HLLW.Antinny.

Protection

• Virus Definitions (LiveUpdate™ Weekly) March 24, 2004
• Virus Definitions (Intelligent Updater) March 19, 2004

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: High
• Deletes Files: Deletes files on C:
• Releases Confidential Info: Uploads personal information to the file-sharing network.

Distribution

• Distribution Level: Low
• Target of Infection: Winny file-sharing network

TECHNICAL DETAILS

When the worm is executed, it does the following:

1. Displays a fake error message or opens a text file that the worm drops.
   
   
2. Copies itself as one of the following to a randomly selected folder:
   • Svchost.exe
   • Spoolsv.exe
   • Explorer.exe
   • Winlogon.exe
   • Explorer.exe
     
     
3. Selects an existing file at random, then copies itself as a randomly named variant of that name. For example, if the worm selects the file name Graph8.exe, it could copy itself as Graph857d0.exe in the same folder as Graph8.exe.
   
   
4. Adds the value:
   
   "<randomly chosen program name>"="<path to worm>" </logon, /start, /autorun or /startup>
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   so that W32.HLLW.Antinny.G runs when you start Windows.
   
   
5. Attempts to delete the files on the C drive.
   
   
6. Overwrites %Windir%Regedit.exe and %System%Regedt32.exe with Notepad.exe.
   
   
7. Locates the name, organization, and email address from the registry, and then creates a text file using that information.
   
   
8. Copies itself to the upload or download folder of the Winny file-sharing program as a file name that is randomly selected from a list of Japanese words, which is contained in the worm.
   
   
9. Creates an HTML file that will execute the worm. The file has the .htm or .folder extension. The .folder file has a standard Windows folder icon, but it may run if you double-click it.
   
   
10. Takes screen shots as .jpg files and puts them in the Winny upload or download folder.
    
    
11. Creates a .zip or .lzh archive that contains the information described in steps 7 through 10. It randomly selects files on your computer and copies the archive file to the upload or download folder. This will distribute your personal information through the Winny file-sharing network.

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

Removal using the W32.Antinny Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.HLLW.Antinny.G. Use this removal tool first, as it is the easiest way to remove this threat.

Manual 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.Antinny.G.
4. Restore regedit.exe or regedt32.exe.
5. Delete the value that was added to the registry.
   

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"

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Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.

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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.Antinny.G, write down the path and file name, and then click Delete.

4. Restore regedit.exe or regedt32.exe
The file Regedit.exe must be restored for all the Windows operating systems. In addition, if you are running Windows NT or 2000, you may want to also restore Regedt32.exe.

The following documents provide general instructions on how to extract files. This information is provided for your convenience. The exact steps may vary slightly depending on the configuration of your operation system, the location of the files, and so on. For additional information, read the Help files, contact Microsoft, or a qualified computer consultant.

• The Microsoft Knowledge Base article, "How to Extract Original Compressed Windows Files," Article ID Q129605, has detailed information for Windows 95/98/Me
• "How to extract files in Windows 98 and Windows Me"
• "How to extract files using Windows 2000 or Windows NT 4.0"
• "How to restore system files in Windows XP"
  

5. Deleting the value from the registry

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WARNING: 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.

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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:
   
   <randomly chosen program name>=<path to copied worm> ( with /logon, /start, /autorun or /startup  option)
   
   
5. Exit the Registry Editor.