W32.HLLW.Parved

SUMMARY

W32.HLLW.Parved is a network-aware worm that attempts to replicate across the open network shares. The worm copies itself to the remote computer using many different names carried by the worm. It also uses an icon typically associated with a Shockwave Flash file.

This threat is written in the Borland C++ programming language.

NOTE: Definitions dated prior to January 8, 2003 may detect this threat as a Trojan Horse.

Protection

• Virus Definitions (LiveUpdate™ Weekly) January 8, 2003
• Virus Definitions (Intelligent Updater) January 8, 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

Distribution

• Distribution Level: Medium
• Shared Drives: Attempts to copy itself to the network shared folders

TECHNICAL DETAILS

When W32.HLLW.Parved runs, it does the following:

1. Copies itself as C:\%System%Devpar.vxd.
   
   NOTE: %System% is a variable. The worm locates the Windows system folder and copies itself to that location. By default, this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows 2000/NT), or C:WindowsSystem32 (Windows XP).
   
2. Sets itself to run when any other executable files are run, by modifying the (Default) value of the registry key:
   
   HKEY_LOCAL_MACHINESoftwareCLASSESexefileshellopencommand
   
   to:
   
   C:\%System%DEVPAR.VXD "%1" %*
   
3. Checks to make sure that only one instance of the worm is running in memory, by creating a mutex with the name "MacromediaFlashPlayer."
4. Inventories all the resources on the network. For each share that the worm finds, it copies itself as one of the following:
   • Bill Clinton.exe
   • Microsoft.exe
   • BIN Laden.exe
   • Nice Holiday.exe
   • Twin Towers.exe
   • Fishing.exe
   • The Black Hole.exe
   • Pretty Woman.exe
   • Anime.exe
   • Internet.exe
   • Office 2000.exe
   • Microsoft XP.exe
   • Hollywood.exe
   • James Bond.exe
   • Jennifer Lopez.exe
   • George Clooney.exe
   • Harry Potter.exe
   • Solaris.exe
   • Muppets.exe
   • Linuxxx.exe
   • Unixxx.exe
   • Mickey Mouuse.exe
   • Donald Duck.exe
   • Uncle Scrooge.exe
   • Fifth Avenue.exe
   • Chrysler.exe
   • Bultaco.exe
   • Laser Games.exe
   • Software.exe
   • Hardware.exe
   • Fantasy.exe
   • Bowling.exe
   • Folklife.exe
   • Money.exe
   • Trade Policy.exe
   • Environment.exe
   • Drunk Driving.exe
   • Cyberspace.exe
   • Internet.exe
   • Geography.exe
   • Gifts.exe
   • Tobacco.exe
   • Office.exe
   • Work.exe
   • Cats.exe
   • Dogs.exe
   • Ducks.exe
   • Sony.exe
   • Intel.exe
   • Macromedia.exe
   • Pioneer.exe
   • Bazooka.exe
   • Excel.exe
   • Power Point.exe
   • Microsoft Word.exe
   • Open Source.exe
   • The Flinstones.exe
   • Newsgroup.exe
   • Tactical Weapon.exe
   • Harry Potter.exe

Because the worm does not properly handle the network resource types, it may cause shared printers to print garbage.

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

NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Reverse the changes that the worm made in the registry key:
   
   HKEY_LOCAL_MACHINESoftwareCLASSESexefileshellopencommand
   
2. Update the virus definitions.
3. Run a full system scan and delete all the files detected as W32.HLLW.Parved.

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

1. Reversing the changes the worm made in the registry
Because the worm modified the registry so that you cannot run the .exe files, first make a copy of the Registry Editor as a file with the .com extension, and then run that particular file and edit the registry.

1. Copying Regedit.exe to Regedit.com
   1. Do one of the following, depending on the operating system you are running:
      • Windows 95/98 users: Click Start, point to Programs, and then click the MS-DOS Prompt. (This opens a DOS window at the C:Windows prompt.) Proceed to step 2 of this section.
      • Windows Me users: Click Start, point to Programs, point to Accessories, and then click the MS-DOS Prompt. (This opens a DOS window at the C:Windows prompt.) Proceed to step 2 of this section.
      • Windows NT/2000 users:
        1. Click Start, and then click Run.
        2. Type the following, and then press Enter:
           
           command
           
           (An MS-DOS window opens.)
           
        3. Type the following, and then press Enter:
           
           (cd winnt)
           
        4. Proceed to step 2 of this section.
      • Windows XP:
        1. Click Start, and then click Run.
        2. Type the following, and then press Enter:
           
           command
           
           (A DOS window opens.)
           
        3. Type the following lines (Press Enter after typing each one.):
           
           cd
           cd windows
           
        4. Proceed to step 2 of this section.
           
   2. Type the following, and then press Enter:
      
      copy regedit.exe regedit.com
      
   3. Type the following, and then press Enter:
      
      start regedit.com
      
      (The Registry Editor opens in front of the DOS window.)
      
      
B. Editing the registry and reversing the changes that the worm made

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. Navigate to and select the following key:
   
   HKEY_LOCAL_MACHINESoftwareClassesexefileshellopencommand
   
   CAUTION: The HKEY_LOCAL_MACHINESoftwareClasses key contains many subkey entries that refer to other file extensions. One of these file extensions is .exe. Changing this extension can prevent any files ending with an .exe extension from running. Make sure that you browse all the way along this path until you reach the command subkey.
   
   Modify the HKEY_LOCAL_MACHINESoftwareClassesexefileshellopencommand subkey, shown in the following figure:
   
   <<=== NOTE: Modify this key.
   
2. In the right pane, double-click the (Default) value.
3. Delete the current value data, and then type: "%1" %* (That is, type the following characters: quote-percent-one-quote-space-percent-asterisk.)
   
   NOTES
   • On Windows 95/98/Me and Windows NT systems, the Registry Editor automatically encloses the value within quotation marks. When you click OK, the (Default) value should look exactly like this:
     
     ""%1" %*"  
     
   • On Windows 2000/XP systems, the additional quotation marks will not appear. When you click OK, the (Default) value should look exactly like this:
     
     "%1" %*
     
   • Make sure that you completely delete all the value data in the command key before you type the correct data. If you leave a space at the beginning of the entry, any attempt to run the program files will result in the error message, "Windows cannot find .exe." If this happens to you, restart the entire process from the beginning of this document. And, make sure that you completely remove the current value data.

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 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.

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.Parved, click Delete.